There has been a lot of interest at our nursery, and in current plant-breeding programs for smaller shrubs. Most of the old-time favorite shrubs are very large. Most lilacs, viburnums, honeysuckles, forsythias, privets, elderberries, serviceberries, butterfly bushes and hibiscus are 6’-12’ high and often as wide. These are great to provide screening and big masses of color along fences or the back of the border.

But many people these days are not gardening on half-acre lots; or they have been avid gardeners for 10-20 years and have little space left, or they are looking for low maintenance accents that fit into small spaces or mix with perennials. In addition, we garden in Colorado conditions where sweet little things fresh out of east or west coast breeding programs crash in our low humidity, fierce sun, strong wind, shocking temperature changes and alkaline soils.

Yes, we have potentillas and some dwarf spireas, but what other rugged shrubs under three feet high and wide are successful here?

Genista lydia, Dyer’s Greenwood, is a small broom 12”-18” high and 2’-3’ wide. Evergreen arching branches form a compact mound. The leaves are small and the bight yellow, pea-like flowers smother the plant in early summer. This is a tough plant that does well in full sun and low water conditions. It is tolerant of various soil types and seems more cold-tolerant (zone 4) than many Cytisus brooms. Do not over-water or prune back hard. Genista lydia is elegant and fits in both formal and informal gardens.

Clematis fruticosa ‘Mongolian Gold’ is a non-vining shrub 2’ high and 3’ wide. It blooms for two months in summer with pendant, yellow, fragrant bells, followed by attractive smokey seedheads. This bush clematis likes sun and shades its own roots. It is tough, but does not like either bone-dry or soggy soil. The shiny, dark green leaves make a nice effect themselves. My wife, Eve, has been growing this clematis for 10 years and says, “It has never had a bad year.”  It was collected originally in Mongolia, and was chosen as a Great Plants for the Great Plains selection. It is hardy to zone 4.

Amorpha nana is a Colorado native shrub that grows 2’-3’ high and wide. It is distinguished from its better-known cousin, Amorpha canescens, by being green leaved and slightly shorter. Commonly known as Dwarf Lead Plant, it has been called “Dwarf Dead Plant” in spring, since it is so late to leaf out that it is never caught by late spring frosts. The summer-blooming spikes of tiny fragrant purple flowers are both a welcome sight for human eyes and an attraction to many kinds of bees and butterflies. The roots host nitrogen-fixing bacteria. Dwarf False Indigo is another common name for this very drought tolerant native. Prune off dead flower spikes and remove any dead wood in spring when the leaves start to show. It needs little else.

‘Mini Man’ Viburnum is a dwarf Manchurian Viburnam (V. burejacticum), found by propagator Scott Skogerboe at Ft.Collins Wholesales nursery. Typically, the Manchurian Viburnum grows 7’-8’ tall and wide, but this form only grows 3’ for me in dry shade, but could attain 5’ if watered generously. It is very compact, with thick, velvety gray-green foliage that turns burgundy in fall. The blossoms are clusters of small, creamy white flowers that are followed by red fruits that mature to black. It is quite drought tolerant, hardy to zone 3 and is a beautiful small specimen for part shade.

Leptodermis oblonga (False Lilac) is a little known, dwarf, dense mounding shrub from the Himalyayas, gradually reaching 12”-24” high and wide. The pointed mid-green leaves are small and simple. Leptodermis is late to “wake up” in the spring, but be patient; it will produce small, very pretty clusters of violet-pink, tubular blooms in late spring, and again in fall. The flowers attract bees, butterflies and hummingbird. It is rarely troubled by diseases, insects or deer. Leptodermis grows in most well-drained soils in full to part sun with moderate watering. It has been alive in our garden for six years. It is hardy to zone 5 and did die back last winter but is already blooming.

Arctostaphylos x coloradoensis ‘Cascade’ is a manzanita with bright green, evergreen leaves and tiny white flowers blushed with pink, followed by  red berries in fall. It is more compact than many hardy manzanitas, growing 1’-2’ high and 3’-4’ wide. This selection was made by Boulder plant explorer, Alan Taylor. ‘Cascade’ has cinnamon-red to purplish exfoliating bark and, as its name implies, cascades over rocks and banks. It is even successful under evergreen trees. Most manzanitas seem to need moderate moisture the first year or two and then they are fairly drought tolerant.

Daphne susannae ‘Lawrence Crocker’ is a beautiful, small evergreen shrub, 8”-12” high and 12”-18” wide. Its deep pink flowers are very fragrant and cover the plant in late spring, then bloom off and on through the season. Daphne likes our alkaline soil, and ‘Lawrence Crocker’ is happy in part shade or sun as long as it is watered moderately and is protected from winter sun and strong winds. It needs soil with good drainage so maybe add some expanded shale to your dense clay. My wife, Eve, has 3 specimens that all survived last winter. She loves the fragrance, which is worth getting on your hands and knees for the intoxication.

‘Pawnee Buttes” Sand Cherry is a short form of Prunus besseyi, our native Sand Cherry. It blooms in early spring with fragrant white flowers that are very attractive to bees and other pollinators. The shiny green leaves turn red to purple in the fall. Like the taller form, ‘Pawnee Buttes’ produces round, black fruits in the summer that are eaten by birds, but are usually too bitter for humans. Although it only grows to about 16” in height, it can spread up to 4’-5’ wide. Summer pruning of the longer stems and growing in drier conditions can keep this water-wise shrub more compact. It was chosen by Plant Select in 2000.

Other small native shrubs include: Dwarf Rabbitbrush, Snakeweed (Gutierrezia sarothae), Ceanothus fendleri, Purshia tridentata and Holodiscus dumosus.  Non-native small shrubs include Paxistima canbyi, Mahonia aquifolium compactum, ‘Kelsey’ Dogwood, ‘Little Devil’ Ninebark, Thuja ‘Hetzi Midget’, ‘Crimson Pygmy’ Barberry. ‘Prairie Petite’ Lilac and Caragana frutex globosa, and of course many dwarf spireas and potentillas.

Many worthy small shrubs did not make this list: those that are short, but wide spreading, roses, and currants and gooseberries that are mostly 4’ x4’ but have ornamental berries or flowers.

Pruning is good to help keep shrubs in their place. And the word is out from California that you get the greatest dwarfing effect by pruning around the Summer Solstice, June 21.


Planting a tree puts us in touch with one of the most essential parts of a tree that is often overlooked—the roots. When a seed germinates, the first part to develop is the root. The seed has stored nutrients, but if the plant is to live, it must immediately make a relationship with the nourishment of the earth. Then it can make the sprout that pushes into the sunlight to start photosynthesizing. So the first matter of importance in planting a tree is to honor its roots—their condition, their future environment and their nourishment.

But before we dig a hole, we should take into account another matter of importance, namely the elements of size and time, so the right location and choice of tree are essential to tree planting. First determine if you want a shade tree or an ornamental or fruit tree. A shade tree will dominate the landscape. It will cool the house in the summer and provide a shady refuge outdoors. It will also cost more to be pruned and will limit the sun-loving plants that will grow near it. If you do want to plant a shade tree, plant it on the south side or the west side of the house for the greatest value. The late afternoon sun in Colorado is very intense coming through the west windows late in the day. Remember: most rock garden plants, many shrubs and flowering perennials, natives and xeriscape plants need at least 6 hours of direct sun.

An ornamental tree is one that is usually 15’-30’ tall and wide and that flopwers or has ornamental fruits, fall color, attractive leaves or bark. These should also be sited for best effect. They often branch lower than a shade tree and so can provide screening. But if 8’-10’ is enough to provide a screen, it might be better to plant a big shrub. If the tree is evergreen, be careful not to plant it where it will block our valuable winter sun to the  house or where it will shade a sidewalk or entry that will be icy in the winter. Don’t plant a tree under a power line or too close to the house or the sidewalk. Look around the neighborhood to see successful spacings of trees to structures.

Now that we know where to dig the hole, let’s consider how to dig the hole. For this article, I am assuming that we are planting a tree that is in a container. Most balled and burlap trees are too heavy for a homeowner, and I will mention B&B later.

The hole should be the same depth as it is in the pot and a minimum of twice the diameter of the pot and three times the diameter is better. A tree in a 5 gallon pot will require approximately a12” deep hole, a 7 or 10 gallon tree, a few inches deeper. Most tree roots live in the top 8”-12” with some bracing roots going deeper. That is because tree roots need oxygen and the nourishment that is more available in the top of the soil. When digging the hole, I take the top 6” and put it on one side of the hole and put the lower 6” on the other side. Some people like to slope the side of the hole and maybe that is helpful.

Next we must determine what to add to the soil in which we will be planting our tree. It has become popular lately to instruct us to not use amendments, but to plant in the soil just as it is. It is claimed that if we put compost in the backfill that the tree will grow confined and confused as if in a pot or that amendments are not needed. And if I were planting a tree in Iowa soil, I might agree, but I always plant with 1/3 compost and 2/3 original soil. Certainly if we use more than 50% compost we could have problems. And if we plant in unamended soil, most trees will still grow. But these are my reasons for amending: Almost all Colorado soils are low in organic matter and nitrogen. Compost holds water to help get a tree established when it has few roots. Compost opens the structure of the soil allowing rain to penetrate to the roots and allowing air to the roots. It also allows the new hair roots to more easily push through the soil. And compost provides food for the soil life to prosper. These beneficial fungi, bacteria, earthworms etc bring water and nutrients, dissolve minerals and in many ways support the health of the tree.

Besides adding compost we can add microorganisms directly. There is always life in the soil, but we have found by experience that adding some extra at planting, supports a more rapid root development which helps a tree establish faster and to grow more successfully. The first month of a tree’s life after planting is the most critical to its success. We can use a powdered mycorrhizae, wetting the tree roots and dusting on a small amount. We can use a water soluble form and directly apply it to the roots with a watering can, or we can apply a microbe-rich compost tea or even a worm casting tea to the roots before planting. Adding mycorrhizae is most important in new developments where the soil may be trucked-in subsoil with little soil life.

Some trees like pear, apple, crabapple, aspen or birch need ample air to their roots; in poorly drained soils these trees are susceptible to fireblight, fungal diseases or root rot. Especially if the soil is a dense clay or is in a low spot that collects water, it helps to mix 10%-20% Expanded Shale into the backfill. This locally mined shale is fired in a kiln which makes it porous so that it holds both water and air and does not break down over time, like compost does. This makes Expanded Shale a true “clay-buster”. In addition, it may be helpful to add a little organic fertilizer to the backfill. Since our soils are often low in nitrogen, an organic fertilizer that is 3%-8% nitrogen can be helpful. The old warning not to fertilize when planting is only valid for chemical fertilizers that are water soluble and force top growth when the roots need to establish. Organic fertilizers are slow-release, and a half cup to a cup will provide nutrients both for the tree and for the beneficial microorganisms. All these amendments should be added to the top layer of soil taken from your hole.

So now you can take the tree out of the pot. Lift it by the trunk (maybe with a helper) and tap on the edge of the pot all around until the pot falls off. Then set the tree on the ground and tease the roots out of their confined form so they are not circling but are ready to move into the surrounding soil. If the tree has been in the container too long and you can’t pull the roots out of the circling shape, you may have to cut a few roots to open them up. Tip the tree on its side and loosen or cut the roots on the bottom. When a tree grows from a seed, it makes an open root system. So help your new tree with that in mind.

If the ground is dry, put water in the hole before planting, and let it sink in. Then sit your tree in its big hole. The depth is critical. There have been many problems with people planting too deep. This will suffocate the roots and put wet soil against the trunk bark which is not adapted to wet and can rot. This is a common problem with Balled and Burlap trees that are put into containers and “topped-off” with soil. The over-reaction to this is planting too high. This is also a problem because the roots are not designed to be in the sunlight and air, and the tree will dry out out, even if it is drought-resistant. When I interviewed the late, great tree scientist Alex Shigo in 2000 for the Colorado Gardener, he said, “Why not plant a tree at the correct depth? Where the trunk flares should be the ground level.” You can place a board across the hole level with the ground to check where the soil level will be on the trunk. Then if it is too high, dig a little deeper and if it is too low, lift out the tree and add a little soil. If you have to add a lot, tamp the soil so the tree does not settle too deep. Now wet the roots with mycorrhizae.

Then add the amended backfill soil 3”-4” at a time firming a little with your hands, adding water and then some more soil until it is filled to the proper depth. Now take the subsoil on the other side of the hole and make a little berm around the tree, the same diameter as the hole and fill that with water. If you have planted the tree in a lawn, you can place a tree ring 1” thick and 2’-3’ in diameter around the tree. They are made of recycled rubber that lets water through but keeps weeds and grass from growing near the trunk. This is very important to keep mowers and weed trimmers from damaging the young tree trunks. If not in a lawn, the berm-well can be filled with 2” of wood chip mulch. Be sure this mulch is at least 2” from the trunk, because wet mulch can rot the bark.

It can be very helpful to use a tree wrap to prevent sun scald, to prevent rabbits from eating the bark and deer from shredding the bark with their antlers in the velvet stage. The thin bark of a young tree can be damaged by our stronger winter sun, especially if the tree was grown in Oregon. In the old days when a tree was dug, the south side of the trunk was marked and then oriented in the same direction when it was planted. Paper tree wraps can hold moisture against the bark, and are only supposed to be left on through the winter. I like the plastic spiral tree wraps that shade and shield the trunk from animals, but allow air to circulate underneath.

A potted tree rarely needs staking, because the top is not that big and it is better for strong trunk development for it to flex in the wind. If there are broken branches or dead branches or stubs, these can be removed, but a young tree benefits from every leaf that photosynthesizes. If the tree is very tall and whispy, then tip no more than 10% of its height. Otherwise, leave the pruning for a later year.

A company selling Balled and Burlap (B&B) trees has advertised, “Plant a tree, not a stick”, and certainly a new containerized tree can be very small, but it has a developed root system and will begin growing immediately. Many B&B trees are successful, but when they are dug in the field, 50%-90% of their roots are left in the ground, so they are naturally stressed and can take one or two years to start growing.

Alex Shigo instructed us to “Touch Trees”. If we touch our tree to be planted with care and with the knowledge that it can live long and will often benefit others beyond our own lifetime, then we will see that it is well-planted.



Trees do a lot for us humans, so we shouldn’t forget to give them some support. When I look at the treeless ten acre lot next to our nursery, or when I see an old photo of the CU campus with bare land around Old Main, I remember why we can’t take trees for granted in Colorado. Trees really have it hard here, but there are things we can do to help them survive and thrive.

To begin, we must choose tree varieties that like Colorado conditions. The CSU website has a very valuable downloadable resource to help us, the Front Range Tree Recommendation List. 250 trees were evaluated by local experts and the trees are rated A thru D for their success. Just because you see stunning photos or have fond memories of Pin Oaks, Red Maples and Bradford Pears doesn’t mean they will thrive in our alkaline soils, violent temperture swings and the worst fireblight in the country. For example: never plant an apple or pear that is not resistant to fireblight. A Radiant Crab is rated “A”, a Royalty Crab “D” because of fireblight. And our alkaline soils make certain nutrients, like iron, less available, resulting in weakened trees of some varieties.

And it is important where you buy a tree. Trees are not well cared for in Big Box stores and a stressed tree is a poor investment. Some Balled-and Burlap trees come from Oregon or other dissimilar environments. B&B trees do better if they are locally grown. They also do better if they are not too big. People want to start with a big tree, but the bigger the trunk diameter, the more roots that are left in the ground when they are dug. A tree with a 2” trunk diameter will need less water to establish and will be less stressed than a 4” diameter tree, and will start growing faster.

With our average annual rainfall between 12” and 20”, we have to water most trees, and lawn irrigation systems are not designed for trees. Most trees want deeper and less frequent waterings than bluegrass lawns. In fact most trees would be a lot happier outside a lawn. Jack Phillips, principal of New Tree School, has said “Trees did not evolve in landscapes dominated by lawn…Progressive tree care requires a movement away from green sterility and toward a wilderness in soil.”

What Jack means is that not only does grass drink a tree’s water and starve it for oxygen, chemical lawn care starves it for organic matter and kills off the soil life that are a tree’s allies. Trees need less water in spring when we have precipitation and twice the watering in July when it is so hot and dry. Remember: soggy soils have little space for air, and trees need oxygen to their roots as much as they need water.

Because of our dry autumns, sunny winters and winter warm spells it is very helpful to trees to winter-water, especially evergreen trees and trees planted in the current year. Water early on a sunny day to give time for the water to soak in before night-time freezing. Water long enough to penetrate 6”-8”. No need to water if the ground is frozen. A sprinkler works better than a deep-root needle. Remember: Colorado is in a semi-arid region, we are a mile closer to the sun and we lack the winter cloud cover of the regions where many of us grew up, and where most of our trees originated.

Our soils are not the rich glacier deposits of the Midwest. Clay is okay, but it needs more than water to grow strong trees. There are exceptions: native oaks, Russian Hawthorn, Boxelder. But unamended Colorado soils are all deficient in organic matter and nitrogen, from a tree’s point of view. There are those that disagree with me, but I will stand my ground, based on 35 years in the tree care business.

I do not believe in using chemical fertilizers which are made from natural gas, lack micronutrients and are water soluble, pushing fast growth that is soft and susceptible to fungal diseases and sucking insects. I do believe in planting a tree with 30% compost and a little organic fertilizer. And I think periodic feeding with an organic fertilizer and minerals is good, especially if you also are giving the tree some mycorrhizae and mulching over the root zone. I favor this approach because I believe it is necessary to make up for the lack of natural pile-up of leaves and branches that feed the soil on the forest floor. Yes, there are already mycorrhizae in our poor soils, but experience shows that trees establish faster and have fewer disease problems and need less water when humans give them a good mycorrhizae supplement or compost tea. And yes, trees will grow without fertilizer, but not only will they grow faster, but trees with good nutrition will be stronger and more able to cope with Colorado’s harsh environmental conditions. The two best times to fertilize are early spring and early fall and the best time is early fall, because that is when trees are storing nutrients in their roots and stems. This is where the energy will come from if they have to make a new set of leaves after a late spring freeze or to ward off an insect or disease.

According to research done by Ralph Zentz, a Ft. Collins city forester, 70%-90% of all tree problems are abiotic. That means few tree problems are caused by insects and diseases; most are caused by environmental and cultural conditions. This is good news since it means,  we can generally support our trees without spraying anything or having to pay to have something (especially something toxic) sprayed on our trees. So choose a tree that likes Colorado, plant it in the sun or part shade if it prefers, water it deeply and infrequently and once a month in the winter, prune it correctly, and give it organic nutrition so that its soil allies will prosper. Then it will have the vitality to breathe carbon from the atmosphere and build a structure that stands the wind and snow, and provides shade, fruit, beauty and habitat.

Cherry Trees on the Front Range

According to some reports, Colorado weather in 2014-2015 has resulted in the deaths of 80% of our cherry, plum and peach trees. How did this happen? Does it make sense to replant? And if so, how can we reduce future losses and increase fruitful successes? This article will focus on cherry trees.

The Colorado Front Range is well known for our normally difficult gardening conditions: low day-time humidity, large day-night temperature variations, abrupt weather changes, many mild winter days with occasional extreme cold, some extremely early snows (Sept) and late snows (May/June), occasional major wind storms and common hail storms.

But in 2014, a long, mild fall kept plants green and growing into November when temperatures dropped from the 60s to well below zero in 2-3 days. When plants have not gone dormant, the water in their cells freeze, and the ice crystals rupture the cells, damage tissues and damage or kill fruit buds. If cold is more gradual, a layer of cells forms between the leaf stem and the branch, cutting off sap to the leaf. Then as the green chlorophyll diminishes, the less dominant pigments of yellow, orange, red and brown create the fall colors. Soon after, the leaf falls. If the cold occurs suddenly, the corky layer has not had time to form between the leaf stem and the branch, the leaves flash freeze and eventually fall, leaving openings into the tree through which fungal diseases can enter. This can cause serious die-back of branches and even death. This occurred around 1990 when large numbers of Siberian Elms died and died-back. And it happened again because of the November, 2014 deep freeze.

Boulder County Extension Agent Carol O’Meara, reported that the combination of the November flash freeze, followed by the Mother’s Day snow, followed by a very cool, wet May, caused damage and stresses that favored cytospera canker disease and left many fruit trees dead, damaged or fruitless.

According to the 2014 Climate Change in Colorado report, Colorado temperatures have already warmed by 2 degrees F. over the last 30 years, and could warm 2 ½ to 6 ½ degrees more by 2050. This could lead not only to drier conditions, but also to extended warmer Autumns, which could trick trees into delaying dormancy.

With these weather issues in mind, does it make sense to plant fruit trees like cherries here on the Front Range of Colorado? Of course I’m prejudiced because I have a plant nursery, but I would say, yes! Historically there have been a lot of orchards in Denver, Boulder, Lyons, Loveland and Ft. Collins. The 1935 census showed 516,000 cherry trees growing in Colorado, with one orchard in Loveland being the biggest cherry orchard west of the Mississippi. Drought, late spring freezes, 41degrees below zero in 1951, and a shortage of canning supplies caused by WWII destroyed the pie cherry industry in Colorado. However, as many of us know, tart cherries are often very productive in our area, providing wonderful eating and healthy benefits for us.

So which cherry varieties should we be growing and how should we cultivate them?

First, it is good to discuss cherry rootstock, as most cherry trees are produced by grafting in order to duplicate a named variety. It was found that Prunus mahalab was a better rootstock than Prunus mazzard, because P. mahalab produced faster growth, was more tolerant of alkaline soils and is better adapted to drier conditions. Some wilder forms of tart cherry can be reproduced by suckers, but these form thickets. In the old days some cherry orchards grew trees from seed.

The most common variety of sour cherry (Prunus cerasus) grown for the pie-cherry industry in the 30s and 40s was Montmorency. It is still very popular and usually successful. It is a cross between a sweet cherry and Nanking Cherry (Prunus tomentosa). Montmorency is very productive, very flavorful, highly valued today for its anti-inflammatory qualities, the most popular with birds (they know), and hardy to zone 4. It grows 12’ high by 15’ wide. Many Montmorency trees died or died back in the 2014 deep freeze. However it is still a good tree, and since stone fruit trees are rarely strong and healthy for more than 15 years or so, it is good to replant a new one every 10 years, anyway.

Bali Cherry is my current favorite. It is a Canadian variety, hardy to zone 3, and it did not die last year. The fruit is sweeter than Montmorency, and the tree grows to 12’. North Star Cherry is a natural dwarf to only 6’-8’ and is the easiest to net by tying the netting to the trunk which prevents birds from getting trapped. It is a good tasting tart cherry and is hardy to zone 3 or 4. Meteor is a tart cherry, zone 4, that blooms one week later than Montmorency. Mesabi is a cross between a sweet and a tart cherry. It grows 10’ high and 15’ wide, and is hardy to zone 4. These tart cherries are all self-fertile, so they do not need a pollinator. They are hardier than sweet cherries, have fewer diseases and are more tolerant of hot summers and harsh conditions.

Most Sweet Cherries, Prunus avium, are only hardy to zone 5, bloom earlier and are therefore more vulnerable to late frosts and seldom fruit here. Most sweet cherries on the Front Range died last year. Many new varieties are being bred so there is hope that one may be hardy and successful here.

There is a relatively new Canadian bush type cherry that may be useful here. The most often available are Carmine Jewel and Crimson Passion. They are hardy to zone 2 or 3, have full-sized fruit that is classified as sour, but is said to taste sweet. They grow on a 6’ bush, and are self-fertile but more productive when pollinated by Nanking Cherry.

There is also a selection of Nanking Cherry called ‘Orient’ that has a flavor superior to the species and with fruit that is slightly smaller than a tree cherry.

Cherries do best in well-drained (not wet) sandy loam soils with some organic matter, like compost. They prosper when fertilized in the fall with an organic fertilizer, and watered once a week, especially when the fruits are maturing. They appreciate some pruning but do not remove more than 15-20% yearly. You can lighten clay soils to improve their performance, by adding expanded shale to the planting mix 10-20% by volume.

If you are replanting, it best not to plant in the old cherry location. Stop watering in October to encourage dormancy, then water right before a cold period because moist soil holds heat better and the extra humidity results in the air cooling more slowly. Planting near a building, a big rock or on the north side of a building can moderate temperature swings.

Remember that home-grown fruit is fresher, can be left to ripen on the tree, which makes it sweeter, and often comes in quantities that can be shared or bartered. If a 10-20 year-old fruit tree dies in an extreme weather event, it is likely that if you plant another, it could live as long or longer. But if Climate Change does bring more extremes, pay attention to the varieties that survive and thrive in these extremes. This is the best opportunity to select the new plant variations that have adapted best.

P.S. Regarding our climate, don’t be fooled by references to The Colorado Freeze, which was established in 2014 with the hope of bringing women’s tackle football back to the Denver area.


Trees have it hard in Colorado. If it’s not the shallow and lean topsoil, it’s the low rainfall and low humidity, or it’s the heavy wet late spring or early fall snows, or like last November, it’s the dramatic temperature changes. After a warm and beautiful fall without a killing frost until November 11, we experienced a 77 degree drop in temperature between November 10 and November 12. This was one of the three largest temperature drops ever recorded in the Denver area, the other two were in December 2013 and January 2014.

This record is significant to trees and plants because they need time to adjust to cold. They need to harden-off, to form a protective layer between the leaf stem and the branch, and to move the sugars from the leaves down into the stems and roots to store food for spring growth, flowering and fruiting. So now we are seeing the effects of freeze damage and stress especially in evergreens and broadleafed evergreens. We will see dead tips and dead branches in the deciduous trees and shrubs once they have leafed out. And there could be extensive damage if the leaves that did not fall off have left openings into the plants for fungal diseases to enter. This happened around 1990 when major portions of Siberian Elms died off due to fungal infections.

However don’t be in a hurry to cut out unsightly dead branches, because coming out of dormancy can be delayed by shocking conditions. There are a couple tests you can use to see whether a branch is dead or just slow to leaf out: use a finger nail to scratch a little bark off and look underneath. If it is green, it is alive; if brown (and wrinkled) it is dead. And press against a bud; if it is flexible, it is alive; if it is dry and breaks or crumbles, it is dead. If in doubt, wait and see.

Once you are sure a branch is dead, it is best to cut it off because dead material is what attracts the decaying fungi. Decay is great in a compost pile, but  decay in a  shrub or tree branch can spread down into live wood and weaken or deform the structure. And so it is essential that you make the pruning cuts properly, because bad pruning can make the problem worse.

The late Dr. Alex Shigo, who spent his lifetime dissecting, researching and watching how trees respond to wounding and pruning, discovered the “branch collar”. He showed that if we cut through the protection zone represented by this swelling at the base of most branches, decay will more easily enter. Some people, including teachers and professionals, believe that leaving the branch collar means leaving a stump or stub. This is not correct, because the shrub or tree cannot grow over a stump and it will leave an opening into the plant for years that can lead to decay or diseases.

The illustration shows the cut D as one that leaves a stump, the cut A-C as a flush cut that removes the branch collar and the protection zone. The cut A-B is the correct place to cut that leaves the branch collar. It starts just outside the bark ridge and slopes out slightly so as to leave the swelling. Notice there is no stump remaining after this cut. The other illustration shows the decay that follows a flush cut, on the left, and the smaller decaying area from a correct cut on the right. Trees and shrubs do not really heal like animals, they wall off decay so that it cannot spread, but the old tissue is not renewed. Therefore we should not cut off the branch collar and the protection zone.

When the dead wood has been removed, then other helpful pruning can be done. Thinning cuts can remove rubbing or crowded branches. Branches need room to grow and they need light for photosynthesis and for good air circulation and health. Some larger branches may need to be thinned, but cuts close faster and there is less suckering response when thinning is done in the smaller wood.

After storm damage or freeze damage, and subsequent removal of broken or dead wood, a shrub or tree may be misshapen, out of balance, or just plain ugly. The branches that were not broken or dead will grow faster and sprays of sucker growth often grow from the large cuts. This can be corrected, but may require two or three prunings over as many years. It is good to stand back from the tree or shrub and view it from several angles. Like any sculpture, it should look good from all sides. Beauty and balance and proportion are connected. So after the damage is removed, if the resulting shape is one-sided or awkwardly off balance, shorten the long branches by 10%-20%. For optimal structural strength, the tallest branches should be positioned over the trunk. When shortening a branch, it is important to leave a “leader” or side branch at the very end. This leader should be no smaller than a third of the diameter of the branch where it is cut.

Stressed and damaged trees and shrubs also appreciate some other support. If natural rain or snowfall is not enough to make the soil moist, water deeply every 10 days to 2 weeks. This watering can be combined with mild fertilization. You may have heard that it is not good to fertilize a stressed tree. I believe that recommendation is only valid for chemical fertilizers. Our soils are not naturally rich. Most are deficient in organic matter and nitrogen. In addition, our alkaline soil pH reduces the availability of some minerals. Because weakened plants regrow more slowly and are more vulnerable to pests, I would suggest broadcasting a mineral supplement and an organic fertilizer, at half the usual rate, over the root zone and watering it in slowly over a long time. There is no value in watering near the trunk since most of the absorbing roots are located in a wide area near the drip-line (the ends of the branches). You can also use a yucca extract, like Sledgehammer, which breaks down the surface tension of water improving absorption of water and nutrients into the roots and through the cell membranes.

It can be discouraging to see a lot of dead wood and an ugly form, but if the plant has a healthy root system, it can regrow and recover much faster than another new plant. Correct pruning will provide the training. If the tree or shrub is too old and decayed with a weak root system, is diseased, split or just doesn’t have the strength to come back, you will know by mid-August/September, which is good time for planting.

Mikl Brawner was an arborist for 35 years. He and his wife, Eve, are co-owners of Harlequin’s Gardens, which specializes in organic veggie starts and herbs, natives, sustainable roses, xeriscape, unusual perennials, and products to build healthy soils.


Parsley is not merely a garnish. Besides its wide-ranging multicultural culinary uses, it has, like many culinary herbs, significant nutritional and medicinal values and important roles in the garden. And in Ancient Greece, parsley was used to crown heroes. Every part of the plant is useful.

Parsley (Petroselinum crispum) is an attractive, very cold-hardy biennial herb in the Apiaceae (bee-flower) family. It is available in flat-leaf and curled-leaf forms, both of which have rich, glossy green serrated leaves on slender stalks. In the first year, parsley continually produces a mass of foliage, which can be freely harvested as needed. Parsley usually survives our winters, and begins to grow fresh foliage the second spring. As the second summer approaches, it stops producing foliage and sends up 2’ flower stalks, which branch indefinitely, holding many flat lacy clusters of tiny yellow flowers, throughout summer. Then it makes seed, and dies. If permitted, it will self-sow and perpetuate your parsley patch forever. If you dig up your plant at the end of the first summer, then you lose the tiny yellow flowers, containing loads of nutritious nectar, that are highly attractive to honeybees, other pollinators (many species of bees and butterflies) and beneficial insects, such as Hover Flies, whose larvae eat aphids and thrips. Like many members of its family, parsley is an essential host plant for swallowtail butterfly caterpillars, so grow enough to feed them, too.

Parsley is also beneficial as a ‘companion’ plant. It is said to increase the fragrance and essential oils of roses growing near it, and to benefit the growth of chives, peppers, tomatoes, carrots and especially asparagus. Avoid planting it near mints and lettuce.

Medicinally, parsley leaves, seeds and root have been used for centuries. It has anti-inflammatory and antioxidant values for relieving stomach problems and rheumatoid arthritis. It is said to inhibit tumor formation, increase circulation and help dissolve kidney stones. Commercial parsley essential oils can be very strong and should be used with caution. Parsley is very high in Vitamin K and rich in vitamins A, C and iron. It is not only nutritious and delicious, but chewing a few fresh leaves is enough to cleanse your breath of garlic or onion odor.

For culinary use, curled-leaf parsley is tasty, but has a milder flavor and stiffer texture than flat-leaf, and is the ever-perky type used to garnish a platter. Varieties include: Triple Curled, Forest Green, Pagoda and Frisca.  But the Italian, flat-leaf type is preferred for cooking and drying. It is commonly used in soups, stews, pesto and curries, and I love it in salads with tomatoes. Varieties include: Giant of Italy, Wild Parsley, Italian Dark Green and Survivor. My wife, Eve, makes one of my favorite summer foods: Quinoa Tabbouleh, with lots of parsley. (see the recipe below). She also sprinkles it fresh over bowls of her Greek Egg-Lemon Soup. Yum!! And a sprinkling of fresh parsley over boiled potatoes, elevates them above bachelor-fare. And parsley pesto is a delicious, vitamin-packed sauce or condiment. Hundreds of years ago, parsley varieties were selected and bred for thick, carrot-like roots, which give parsley flavor to soups, etc., and are known as Hamburg parsley, or Parsley Root. The book ‘Parsley Greats’ offers 100 tasty recipes using parsley.

Parsley is easy to grow in full or part sun in most soils, but it does prefer composted soil, watered once or twice a week. Parsley even does well in containers that can be brought indoors in the winter, where it likes a cool, sunny location and some misting. It over-winters outdoors in the ground and can be mulched with straw or leaves to be harvested through most winters.

The gardener must be patient to plant parsley from seed, as it is slow to germinate. It helps to soak the seed in water overnight just before sowing in early spring, 8-10 weeks before the last frost. It can be sown in the ground, or indoors in pots. Parsley seedlings should be hardened-off and planted out when they are 2” tall.

Parsley is native to the Mediterranean region, and both wild and garden forms were known to the ancient Greeks. Heroes of the Olympic Games were crowned with olive, but for 450 years, winners of other athletic games were crowned with parsley. It was used in cooking in England before the Norman Conquest, and was brought over to America on the Mayflower.

We should all be growing and using more parsley, even if it does get caught in our teeth.

Byline: Mikl and Eve Brawner are co-owners of Harlequin’s Gardens nursery specializing in organic veggie and herb starts, pollinator-friendly, neonic-free plants, hardy roses and xeriscape.


Japanese Beetle is one of the most damaging insect pests in the Eastern and Midwestern US, but until recently, Coloradans were spared that challenge. It entered the US in 1916, but took until 2003 before a population was established in Colorado. This first infestation was in the Palisade area on the Western Slope. Even though eradication efforts were mostly successful there, established populations have been found since 2005 in Pueblo, southern Denver, Englewood, at DU and at Denver Botanic Gardens. Smaller populations are being seen now in Boulder and Jefferson County.

Japanese Beetle is a scarab type beetle about a half inch long, with a metallic green body and copper-colored covers on its wings. In its larval stage, it is a white C-shaped grub, an inch long at maturity. According to our state entomologist, Whitney Cranshaw, adults emerge from soil or turf in late June, July and early August. They only live 4-8 weeks, but can cause significant damage in that time. After mating, the female lays eggs in moist turf, the eggs hatch into grubs that eat the roots of grass. When the numbers of grubs is large, they can kill areas of the lawn. The grubs are mature by September and they burrow down and go dormant over the winter. In spring they feed for 4-6 weeks, then pupate for a few weeks before emerging as beetles.

Japanese Beetle is the most widespread turf-grass pest in the US. The adult beetles eat the foliage and flowers of over 200 species of plants including: grape, crab apple and apple, rose, linden, Norway Maple, birch, cherry, plum, apricot, peach, raspberry, vegetables and some ornamental shrubs. Virginia Creeper and strawberries are particular favorites. Veggies that are eaten are: green beans, okra, corn, asparagus and basil.

Plants that are resistant to Japanese Beetle are: lilac, spruce, chokecherry, elderberry, Bur Oak, Bittersweet Vine, boxwood, forsythia, hydrangea, juniper, mockorange, pear, pine, smokebush, snowberry, Silver Maple, Red Maple, sumac, spirea, yew; as well as coreopsis, larkspur, foxglove, Coral Bells, hosta, poppy, columbine and pansy. Many vegetables are not attractive to them. A few plants act as repellents: catnip, garlic, chives, tansy and annual geraniums.

How can we manage Japanese Beetles to reduce their damage in our gardens and farms?

Cultural Methods: Like most pests, Japanese Beetles are attracted to weaker plants, so we can support soil health with organic matter, micronutrients, minerals, sufficient water and supplemental biology like mycorrhizae and beneficial bacteria. Plant resistant varieties and natives and xeriscape plants. The beetles are very vulnerable when the grubs are small. So xeriscapes that are watered deeply and sparingly will dry out the grubs and reduce their populations. Bluegrass can be allowed to go dormant in July to save water and seriously reduce grub population. Then water normally in September to bring turf out of dormancy. Or just follow CSU advice and “water as deeply and infrequently as possible.” Dr. Michael Klein, a Ohio State U authority on Japanese Beetles has stated that “compulsive overwatering is often to blame for grub damage.” He also recommends cutting grass to a 3” height, making it less attractive to egg-laying females. And he suggests that we do everything we can to prevent adult damage early in the season, because early feeding attracts LOTS of other beetles.

Non-toxic solutions for the grubs: Milky Spore is a bacteria that only affects grubs and must be eaten to work. Apply a teaspoon amount every 4’ and water in for 15 minutes. Though said to be effective, it may take a few years for adequate protection. It is best applied in early Aug/Sept when the soil temperature is above 65 degrees. Montana Cooperative Extension says it does not provide adequate control.

Nematodes of two varieties are effective but do not work in dry conditions, may not overwinter and are pricey.

Dr. Mike Klein recommends the aerator sandals called Spikes of Death. He says that whereas they are not effective for aeration, if you wear them while Dirty Dancing on your lawn in late Spring when the grubs are near the surface, studies have shown a better know-down than from chemical insecticides.

Non-toxic solutions for the beetles; these may not give total control: insecticidal soap, diatomaceous earth, neem that contains its active ingredient azadirachtin.

Some of our Boulder customers have had success with Veggie Pharm, a solution of vegetable oil, garlic, rosemary and peppermint; and a thyme based spray with Wintergreen called Garden Insect Killer by Liquid Fence is also said to kill the beetles.

Of course hand picking is effective. A bucket of soapy water can be held under the plant while knocking the beetles off into the bucket. This is best done in the early morning when the beetles are slower.

Lower toxicity solutions: Pyola-a combination of pyrethrins and canola oil, and other pyrethroid products do break down faster than more toxic pesticides, but they are still lethal to bees, birds, fish (and cats?). There are many variations.

Higher toxicity solutions: The Colorado Dept. of Agriculture says, “Historically this insect is a target for large amounts of insecticide use.” Organophosphates as well as Neonicotinoids are used. The Palisade Colorado population was nearly eradicated using two different neonics: Merit and Arena. But because neonics kill or undermine the health of most insects including bees, earthworms, lady bugs and beneficial insects, they are not a sustainable solution. And because they are systemic and always in the plant, they do not work in an IPM (Integrated Pest Management) program. Birds that feed on the beetles can also be killed.

Traps: using floral or sex-attractant scents do attract the beetles, but are not considered a solution since they usually increase insect damage.

Japanese Beetle is yet another foreign pest that does not have natural enemies here. Since it is new to us, we will have to watch, experiment and learn more to keep their populations below damaging levels.

New sightings of Japanese Beetle should be reported to the local CSU Cooperative Extension office.

Testing Xeriscape Groundcovers


Whether this turns out to be a drought year or not, the idea of conserving water is probably as vital to our future as educating our children. As long as the human population grows, the demand on our water reserves will continue to rise, forcing eventual water-rationing even if the supply stays the same. And as we have seen this year, we can’t count on a bountiful supply from the heavens. Ten years ago these ideas, and the fact that my own water source is a very low-producing well, got me to thinking about how much water we use in Colorado to water our lawns. We know that xeriscape plants use less water than bluegrass, so why couldn’t we use large areas of certain low-water plants to replace lawn, which could greatly reduce the demand on our valuable water? In order to test a variety of xeriscape plants that might function as replacements for Kentucky Bluegrass, I built a 104′ x 6′ demonstration garden which will be on the 2002 Xeriscape Garden Tour, taking place in Boulder June 29th and 30th.

No plant tolerates sports and children’s play as well as turf grasses and thankfully there are now better and more xeric turf alternatives to Kentucky Bluegrass. However, many landscapes have large expanses of bluegrass that get only occasional foot traffic, often only when they are mowed. At the same time our American yards are often so big that tearing out the grass and putting in lush gardens would require the care of a full-time gardener, and most of us can’t afford the time or the money for that. But what if we could plant big patches of xeric ground covers that would use half or even a quarter of the water of bluegrass, be less time-consuming to maintain than a perennial garden, and could still give the satisfactions of flowering, winter interest and personal character? I decided to test at least 60 ground covers that might be successful in replacing a lawn.

I knew it might take years of experimenting to find the best ground covers to take the place of turf grass, so I sent a survey to about 25 professionals in our rich community of horticulturists and gardeners. I asked them to name 5 or 10 ground covers using these criteria:

1.Needs half the water and half the fertilizer of bluegrass.
2.Has few if any pest problems.
3.Grows densely so as not to require much weeding once established.
4.Looks good in most seasons.
5.Withstands occasional foot traffic.
6.Is not hard to weed out of perennials. I was very pleased to get excellent suggestions from Jim Knopf, Panayoti and Gwen Kelaidis, Lauren Springer, Bob Howard, Marcia Tatroe, Homer Hill, Barbara Hyde, Alison Peck, Mike Woods and others. This was in 1993.
I realized that even the best plants wouldn’t fare well with the bindweed that invades everything on my land, so I decided to build short concrete walls to make it easier to keep out the bindweed and to separate the varieties of groundcovers. These beds contained sections for 66 different varieties, providing a 3′x3′ area for most of them, to show what a good-sized patch would look like. This was completed in 1996.

The next year, Paul Lander of the Boulder Water Conservation Department came out to see my xeriscape rock garden in July and asked about the empty concrete beds. I explained my project and he suggested that I apply for a city grant. Such a demonstration garden has the potential to save the city of Boulder a lot of water, so I was granted enough money to pay for a good drip irrigation system, an occasional truck-load of water and two water meters which could confirm the water-requirements of the ground covers.

For the next three years circumstances of my personal life denied me the possibility of carrying on, but finally the irrigation system went in and I planted in the fall of 2000 and the spring of 2001. Ten years after it was begun, the project is nearly completed. For the next few years I will replant some, replace a few and keep taking photos and making evaluation reports. Many of these ground covers look very promising. However, the real proof will be when enough people plant them in large areas that we will be able to judge their usefulness in replacing thirsty turf grass.

Here are portraits and reviews of five of the best performers.

Geranium cantebrigiense and Ger.cant.’Biokovo’: the excellent plantsman, Dermod Downs, brought my attention to this plant years ago. What really caught my attention was that I planted it first in the wrong place, in a very sunny, dry and inhospitable location; and even though it suffered through the summers, it wouldn’t die and always bloomed very nicely in the spring. When I moved it to dry shade, it thrived; and it has done well in full sun in my xeriscape demonstration bed. The foliage is light green, very fragrant when rubbed, dense enough to suppress weeds, and it turns red in the fall. It grows 8″ high and can spread 24″ or more in diameter. The flowers are a medium pink, and in the selection ‘Biokovo’ they are a light blush pink. This hardy geranium is a winner.

Delosperma ‘John Proffitt’ (Table Mountain): this variety resembles Delosperma cooperi but is an improvement. The foliage is more substantial, dense, turgid in winter and attractively tinged purple, growing 2—3″ high and 10—20″ in diameter. The flowers are a purple-red to lavender-fuschia with a creamy eye, and they have a very long bloom time. ‘John Proffitt’ is also reported to be more cold hardy than D. cooperi. It is a Plant Select winner for 2002 and though it is supposed to require moderate watering, has done well in my demonstration garden. It is beginning to bloom in May and could be the best performing ice plant I have tried so far.

Achillea serbica: this Serbian creeping yarrow is not like the aggressive rhizomatous Achillea millefolium varieties. Whereas it can spread 18″ in diameter, it is not a thug and can easily be weeded out if necessary. The foliage is very beautiful with narrow, cut-leaf, silver, “evergreen” leaves making a dense mat 4—6″ high. The ½” flowers are pure white with a yellowish eye and are somewhat daisy-like. They are held on 8″ stems and smother the foliage with a blanket of bloom in May/June. The plant is drought tolerant, but may get smaller in desperately dry conditions. Some people think Achillea serbica is a subspecies of Greek Yarrow, Achillea ageratifolia; others believe the two are identical. It makes a fine silver ground cover around red, yellow or blue-flowering upright perennials.

Penstemon pinifolius: Pineleaf Penstemon is quite different from most of the penstemons I know. It is neither a creeping mat-forming type, nor a tall spikey type. Instead P. pinifolius has pine needle-like leaves and has a shrubby habit. The evergreen quality of its winter foliage is outstanding. Often evergreen leaves burn in our scorching Colorado winter sun, but not those of Pineleaf Penstemon. There are several different forms. The most common is 10—15″ tall and 24″ wide; a more compact form is 6—10″ high and 12″ wide. Both have narrow, orange-red tubular flowers that bloom profusely over a long period. In addition it is a long-lived penstemon. There is a yellow-flowered form, ‘Mersea Yellow’ which is similar in size to the compact version, and should be cutting-grown. Penstemon pinifolius enjoys low water conditions with good drainage, but will not tolerate foot traffic.

Woolly Thyme was one of several thymes that performed well in my demonstration garden. It is the well-known gray, ½” high woolly foliage that we see so often. It has a good fragrance, seldom flowers and can get to 3′ in diameter (more often 18″). It works well between flagstones, though it can become too large if the traffic doesn’t wear it down. It’s evergreen foliage looks good in a large area, or planted around perennials. It is known to die out in patches from variously hypothesized causes like lack of water, too much water, not enough aeration in the soil, etc. Its botanical name is Thymus pseudolanguinosus and there is a Thymus languinosus which is, of course, very similar but which is not supposed to rot out as readily. I am also testing this variety.

If you think this article is incomplete, you’re right. A demonstration project must be seen not just heard. However if you go on the 2002 Xeriscape Garden Tour June 29 and 30, I will be giving a guided tour of this demonstration garden at 2 PM both Saturday and Sunday, and you will be able to see all 66 varieties. I’m sure there will be other good gardens to see on the tour as well.

Copyright 2003 by Mikl Brawner

Drought Water Restrictions

Drought, Water Restrictions and Gardening: How Can They Go Together?

I think we were all caught off guard by this drought, by how fast we were forced to see dying trees and brown lawns and by the difficult discipline of watering restrictions. This was especially true in Boulder and Lafayette where mandatory restrictions began in May. Actually, 2002 is the third year in a genuine drought, which some of us without city water supplies can confirm. This year all around Boulder, Red Twig Dogwoods turned brown, linden leaves were scorched, Norway Maples suffered, many viburnums were looking very stressed, and trees in medians defoliated or died. Gardeners caught in the crunch between weeks of hot, dry weather and few opportunities to water, held off most of their planting projects; some started talking about moving away to where they could garden. For Denver and other Colorado cities, next year could be much worse.

Now begins the new education about growing plants while conserving water. We have some experience with xeriscape and its seven principles, but they are no longer enough; we have to go to the next level. We are going to have to be much more careful in our plant selection, and in grouping plants of similar water needs. We are going to have to give closer attention to microclimates: distinguishing the areas that bake from the areas that get some shade, recognizing south from east, noting the protective presence of a boulder, a tree, a shed, a downspout; and mapping the movement of the sun and the reach of the wind. We are going to have to learn how to use our water most effectively. We are going to have to learn more about mulching, about anti-transpirants, and about products and amendments that hold water longer. We may even have to adjust our idea of beauty to include dormant, brown lawns; more modest displays of flowers in the summer months and even dry and drooping foliage, stress and death. We will go through a transitional period which will be frustrating and painful, but then we will figure it out and our gardens will be better adapted. Even if we get our needed snow pack this winter, water conservation will remain a vital concern.

First things first: SAVE THE TREES. Trees in general are not very drought tolerant. We didn’t have urban forests in Colorado until humans started planting them and watering them. Yes, of course, we have cottonwoods and willows along streams and some boxelders too, but most of our trees, especially shade trees, are imported. On top of that, most irrigation systems are designed for turf and assume that if trees are growing in the lawn, they will be watered. In the first place, most turf is watered too shallowly (and Boulder’s 15 minute twice a week restrictions further encourage that problem); and secondly, when lawn watering is prohibited or limited, there is no system in place to water trees except by hand, which then takes too much time to comply with restrictions. Thirdly, trees in cities often have confined root systems, and are often overplanted with grass, perennials and other trees which compete for the water.

These problems became apparent in Boulder this year as trees in small median and parking lot plantings were the first to show stress. The newly planted trees with small and reduced root systems (as with ball-and-burlap trees), and the old and stressed were the main trees to die or defoliate. How the remaining trees are cared for in the coming year or two will be a matter of life and death; they are stressed and more vulnerable to pests and diseases.

Trees do take a lot of our water, but they save water too. This summer some of the only green lawns in Boulder were under trees. If global warming is happening, we will need at least some trees to save us from the heat, to keep the gasoline in our cars from out gassing in the parking lots, and to create moderated environments in which other plants can live. At this time, I will not go into the many values that trees add to our quality of life, but let’s not let our trees die while we’re trying to figure out how to save water. Remember the trees now casting our shade are twenty to a hundred years old; it will take that long to replace them.

Some trees that require little water are: Hackberry, Golden Rain Tree, Ponderosa and Pinon pines; Bur and Gamble Oak; Russian, Toba and Washington hawthorns. Trees with somewhat low water needs are: Silver maple, Green Ash, Honeylocust and Catalpa.

This drought has brought up some new and challenging questions:

1.Do trees take more water than they save? Which ones?
2.Is bluegrass a xeriscape groundcover if we can let it go dormant in the summer?
3.If my plants are dying under the current restrictions of 15 minutes twice a week, can I water once a week for 30 minutes to save them by watering more deeply?
4.If I buy a water efficient toilet which will save 10,000 gallons in a year, why can’t I have at least 5,000 gallons more that I could use for my gardens?
5.How can I recycle or reuse my water?
It is easier to come up with questions than solutions. To be fair to the municipalities, they were caught off guard as much as we gardeners, and it will be some years before they/we figure out how best to distribute our water. Even though my low-producing well has put me on water restrictions for the past 17 years, and all my gardens are by necessity xeriscapes, I wanted to get a broader perspective on this drought, so I asked some good local gardeners how they experienced this year’s water crisis.

I interviewed Lauren Springer, Marcia Tatroe, Bob Nold, Jim Knopf and John Spaulding:

“Did you lose plants to the drought this year?” Marcia lost dozens of plants, most of which were newly planted. Lauren lost both new and established, noting as did John and Bob that the losses were due to the cumulative effect of 2 or 3 dry seasons. Jim lost a few things.

“Were the losses due to the heat or mainly to the lack of water?” Lauren and Marcia thought both heat and drought, though Lauren said mostly lack of water. John said more likely heat because he was watering adequately. And Bob said his died because he was not paying attention to them. He also mentioned that his losses of alpine plants were very low, because they can continue to grow under a wide range of hot and cold temperatures.

In a recent talk, Kelly Grummons mentioned that in general, the metabolism of a perennial slows down above 80 degrees F and nearly stops at very high temperatures. A Boulder city forester told me that the burning leaves of the Norway Maples was due to their heat sensitivity, and it seemed that vegetable gardens that were planted early thrived and those planted late in the heat grew little until temperatures cooled.

“Name plants that did well this year with limited water supply.” Jim: Zauschneria, Buffalo Grass, Hesperaloe, Melons, Blue Mist Spirea, Junipers, Apache Plume; John: roses, and annuals did better under water restrictions where maintenance companies had been over watering

Lauren: Fernbush, Saltbrush, Rabbitbrush, Artemesia versicolor, Wright’s Sacaton, Salvia pachysilla, Apache Plume; Bob said all of his rock garden plants did well; Marcia: Desert Four O’Clock, Russian Sage, Apache Plume, Mt. Mahogany, Leadplant, Desert Mahonia.

“Name plants that died or did poorly.” Lauren: Veronica teucrium, all tall penstemons, carex; Jim: Red Maples, Sugar Maples, Norway Maples, Birches, High Bush Cranberry, Red Twig Dogwood; Marcia: Potentilla atrosanguinea, Ligularia, Eryngium alpinum, Microbiota decussata.

“Do you use a mulch? What do you recommend?” John suggests 2″ of coarse mulch applied only after the soil has been thoroughly watered. He says mulch that is too fine or too thick (4—8″) will not permit water to get through. Bob uses straw or anything organic, but prefers rock as the best possible mulch, allowing water to penetrate and then holding the water for a long time. Marcia uses mulch extensively, preferring pine needles loose or shredded, and chipper chips if they are re-shredded.

John Starnes says he has good results with a 6″ deep wood chip mulch.

“What were your water restrictions and how did they affect your garden?” Lauren’s well went dry May 7 and she had only 7″ of rainfall up to September, so she mostly watered trees, roses and woody plants. Marcia could water every third day as long as she wanted until Sept. and then one hour every third day. She only applied a half inch a week and that was enough. Her dry garden was only watered 3 or 4 times all season. She would prefer a water budget, watering when and how is best for her garden. Bob said his restrictions had no impact since he is used to having no rain and watering everything by hand. Jim noted that his water use went up with the restrictions. He did not like the shallow watering which resulted from Boulder’s 15 minutes twice a week rule. He would prefer more flexibility, measuring use by the water meter.

“Share an insight from your experience of this year’s drought.” Marcia: Most of my trees are small native trees and they did fine, but I recommend putting off tree planting until we see what next years’ water supply looks like. If you do plant one, choose one under one and a half inch caliper with a large rootball, mulch it 6″ deep beyond the width of the rootball, and water it once or twice a month over the winter, and be prepared to carry gray water to it next year.

John: When lawns are installed without proper tilling depth (8—12″) and without compost amendment, they will not be just dormant after a drought, they will be patchy at best or dead in two seasons of restrictions. It is best to start lawns of all types from seed so as not to get a horizontal barrier to water and nutrient movement. Even bluegrass, if done right, can be very disease, insect and drought resistant.

Bob: My bluegrass and turf-type tall fescue were both watered 15-20 minutes every ten days, and both look green and healthy. People should not be allowed to plant trees under water restrictions. Existing water supplies can’t possibly support more trees than we already have. Proper planting in the right place saves water.

Jim: Bluegrass won’t live on two tenths of an inch of water twice a week; patches of grass and bare ground is not a lawn; a half an inch of water once a week is much better. If we had a water budget system, that would allow more opportunities and use no more water. We could then design landscapes that fit the budget.

Lauren: Take care of the trees; this is our most important group of plants. We are lucky to have gardens, and here in Colorado you have to love gardening to put up with the duress, and to struggle with the obstacles. Colorado gardeners have to be tough and optimistic.

We may be going through a painful period, restricting our plant palette, and our freedom to water as we please, but this discipline is probably good, because the earth is not growing with the human population, and we must prepare for conservation of not just water, but of all our natural resources. A friend in Italy has a sign in her kitchen: “When you use THE WATER, give thanks. Can you imagine the world without her.” And another friend, a physicist at the Solar Energy Research Institute, believes a time will come when each person will get an energy allocation as well as a water allocation; and that we will have to make some hard choices between heating the house and miles of driving, for example. Mr. Bush may believe that we can keep coming up with cheap oil and keep sending ever more carbon dioxide into the atmosphere, but I’ll bet a lot of people are beginning to get the picture. As Chief Seattle put it: “The earth does not belong to us, we belong to the earth.” Statistically, average droughts are five years long. If that is true for this drought, we get two more years to figure things out and make adjustments with the pressure of this natural discipline. However droughts can be 10–15 years long, and besides, more houses are being built and so more demand will be placed on the same amount of water.

This may sound grim, but there are plants that are surviving this drought with even less water than restrictions allow: native plants, for example. And my xeriscape got only five waterings this year and still looks all right. And if I make some improvements, it will look even better. We can all share our successes and failures with each other and our gardens will get better adapted to drier conditions. Natural Selection is a ruthless and accurate designer. If, for example, all your Sunset Hyssop (Agastache rupestris) died from drought except one, and it flourished, it may have found the perfect spot, OR if it was seed propagated, it could have a slight genetic deviation that makes it more drought tolerant. So save your seeds from your best drought survivors and share them with your friends and neighbors. A drought cycle is the best time to cull the pretend xeric plants from the truly xeric plants, as well as to discover more drought tolerant strains. If we pool our seeds and cuttings, share our discoveries and insights, and follow these with real changes in our habit patterns and in our gardening, this drought could be a great education for better use of our precious resource: THE WATER.

In future issues of Colorado Gardener, we will go into greater depth on the drought situation and into practical approaches to gardening under drought conditions.

Copyright 2003 by Mikl Brawner

The Pruning and Care of Young Trees

Of all our plants, trees take the longest to develop and so it is not only heart-breaking, but a significant set-back to a landscape when a tree that is 10-20 years old is destroyed in a storm. Many of these disasters could be prevented with proper pruning early in a tree’s life. Besides preventing disasters, pruning trees properly when young will help them to develop more beautifully, make them stronger, less expensive to maintain as they get older and keep them healthier.

A young tree, like any young being, is vulnerable and needs some extra care. And trees are often a costly investment, both for the plant and for the planting. So since few arborists will come out for the fifteen minute job of pruning a young tree, and since few lawn crews are trained in proper pruning, it is good for home-owners to understand the basics of pruning in order to get their trees off to a good start.

For a basic understanding, it is important to learn three fundamentals:

1.The common hazards and how to avoid them.
2.How to make a correct pruning cut.
3.How to train a young tree so it will have a strong structure.
The common hazards to young trees are many, but these are the main ones to avoid. Don’t let lawn mowers or weed trimmers touch the bark. This tearing of the bark, called “lawn-moweritis” is often a cause of disease and decline in young trees. Put a loose protection, like a plastic or hardware cloth cylinder, around the trunk or mulch 2—4′ around the tree so mowers won’t have to come close. A protector will also prevent cats from using a young tree for a scratching post, which is very harmful. Naturally, deer, especially bucks with their antlers in the velvet stage, can destroy a young tree with munching and rubbing. So keep a circle of fencing around a young tree for three or four years if deer visit. If a tree is planted too close to a street or sidewalk, people will start breaking off branches. If you plant under an electrical line, Public Dis-Service will carve a huge hole in the tree’s canopy. If you forget to remove stabilizing ropes or wires, the tree will grow over them, become girdled, and will break off or be seriously weakened. And lastly, beware of human over-reactions. Don’t over-water and don’t expect the tree to live on Colorado rainfall. Don’t prune aggressively and don’t leave the pruning to nature. Don’t pile mulch against the trunk and don’t let the soil bake with no mulch. Don’t plant too deep and don’t plant too high; plant right where the trunk begins to flare into the root. The best pruning cannot make up for these hazards.

Learning how to make a correct pruning cut is of the utmost importance. Since pruning is surgery on a living being, an improper cut will have far more serious consequences than cutting a 2×4 off at the wrong angle. About 20 years ago, Dr. Alex Shigo’s research for the Forestry Service revealed new information about how trees should be pruned. Dr. Shigo identified the branch collar, which is often a swollen area at the base of a branch. He discovered that the common practice of making a flush cut (see Figure 1. A-C) slices through a protection zone at which a tree can wall-off decay. So by making a pruning just outside the branch collar, trees’ natural defenses are left intact. (Fig. 1) What is not simple about this advice is that trees are variable, so there is no simple formula for judging the distance from the trunk or the exact angle for a proper cut. See Figure 2 for variations. Unfortunately, even some university teachers advise their students to leave a short stub (Fig. 1. D), but this will lead to decay. In general, look for the swelling of the branch collar and cut just outside it. If you can’t see a swelling, find the bark ridge (Fig. 1. A), and begin your cut just outside that ridge, sloping the cut out, usually less than 90 degrees from the branch. (Fig. 1. A-B) In most cases it is better to remove the branch in two steps; first take of most of the branch and second, remove the remaining stub. This will prevent splitting and tearing of the bark. Armed with this knowledge, you can remove dead, broken and diseased branches, vertical-growing sucker shoots and rubbing branches.

Whereas learning to make a proper cut is science, learning to create a strong structure is part science and part art. The science is learning what makes a strong crotch, the union of a branch to the trunk or to a larger branch. Basically the strongest branches are at a 60 to 90 degree angle from the trunk. This sounds counter-intuitive since we would normally think that a branch that stands out perpendicular to the trunk would be more likely to break. However the greatest possibility for weakness occurs in branches that are at a 30-degree angle or less, because with these, the wood fibers run parallel rather than interlocking. You can easily tell if a crotch is weak by looking closely where the branch is connected. If the bark is pushed up into the bark ridge (Fig. 1. A), the union is strong. If the bark is folded in, forming a crack, the union is weak, and the branch is likely to fail sooner or later. The most dramatic example is called a co-dominant leader. (Fig. 3) In this case, two branches arise from the same place on the trunk and grow up nearly parallel. You will almost always find the bark folded in between the trunks. As the two trunks grow, they reach for light, leaning away from each other. This makes them vulnerable to heavy wet snows and strong winds, which can cause the tree to split down the middle. (Fig. 4) This usually means the death of the tree.

There are two approaches to dealing with branches with weak crotches and co-dominant leaders. One is to remove the weak branch or less important trunk. This is easiest and least harmful to do when a tree is young. If removing the entire branch or trunk would be too severe, the weak branch or leader can be dwarfed by shortening the branch significantly. This is called a training cut and can also be used to dwarf the height of a tree while it is still young. See figure 6 for the proper method.

The art of creating a tree with a strong structure is learning how to recognize balance and proper proportion. Young trees that are fertilized and over watered often shoot up and become gangly and vulnerable to breakage. Whether a branch is strong or weak is relative to the proportion of length to diameter. This varies with the type of tree, but roughly, a 1″ diameter branch 4′ long can be strong, whereas a 1″ branch 8′ long will be weak. In terms of the overall structure, remember that the trunk is the pillar holding up the entire tree, so the better the top is balanced over the trunk, the stronger it is. If the highest point of the tree is far from being directly above the trunk, the tree is not balanced and will be weaker. The time to correct this is when the tree is young, by pruning the wayward leader back to a branch that will direct the growth more over the trunk. In general, round and conical are the most stable forms in terms of strength.

Storm damage can also be prevented and health supported by removing crowded and rubbing branches. This thinning is best done when the branches are small, and never remove more than a third of the branches.

Especially in very young trees, every leaf adds to their photosynthesis. But also remember that we live in Colorado with high winds and wet snows that sometimes catch our trees in leaf, so it is good to prune to more compact forms than would be necessary in California or even Iowa.

In general, if the proportion of a tree, height to width is pleasing or beautiful, it is stronger. If it is awkward or ugly, it is weaker. And the same is true for individual branches. Be patient with young trees because they often have an adolescent phase before they develop symmetry and real beauty. Be gentle and not too aggressive; don’t top them or chop them. And since it takes little time to prune a young tree, and since they can change so quickly, plan on doing some corrective pruning every year or every other year as needed. Watch the structure as it develops and responds to your pruning. Use your imagination to visualize how each branch will grow. Pruning can be artful, creative and fun. Before long, your care and insight will take form in a massive being that will tower above you and your children and your house, providing shade, protection, character and beauty, and putting that greenhouse gas, carbon dioxide, to a constructive use.