Some Drought-Tolerant Gems

Plants that tolerate or even revel in hot, dry conditions are always in vogue in Colorado. We may be blessed with moisture in the spring, as we had this year, but by June or July our vegetables need regular watering and east coast woodland plants are melting. There are some plants, however that are adapted to hot and dry conditions. Some are natives and some are from other regions of the world that have similar drought stresses as we have here.

         These gems are ones that we have tested at Harlequin’s Gardens where none of our demonstration gardens are watered more than once a week, and others only 5 or 6 times a year. We can recommend these plants as successful and enjoyable under mandated or self-imposed watering restrictions.

         Orange Horned Poppy (Glaucium acutidentatum) is a very showy member of the Poppy Family. The shrubby plant, which can grow to 2’-3’ wide and 18”-24” tall, has bold silvery-blue evergreen foliage, and rich orange 4-petaled flowers with black basal spots. After the very long blooming period from late spring into summer, flowers are followed by long, thin, curved seed pods (the horns). These split, releasing hundreds of seeds. To prevent an over-population, it is advisable after the pods have dried, to save a few in a paper bag to plant in the fall, and to cut the old flowering stalks back to the rosette, removing the majority of seed pods.

         Horned Poppy has a big taproot and is drought-tolerant. In fact, it is so successful, it is on our “watch it” list, to see if it has potential for escaping into the wild. It is a spectacular and beautiful, well-adapted perennial for full sun.

         Saponaria ‘Max Frei’ is a very showy summer-blooming soapwort with one inch rose-pink, five-petaled flowers. This sterile form of Saponaria lempergii is very long-blooming, and is a welcome sight in the doldrums of late summer when its dense mass of color stands out. Although only 6”-10” high, Max Frei Soapwort can spread to 18”. It is generally very tough and easy to grow, but doesn’t like wet conditions with high temperatures. We have noticed it can be vulnerable to a leaf miner that disfigures the foliage. If this happens, cut it back 50%, and it will regrow. It is resistant to deer and is hardy to zone 4.

         Western Spiderwort, Tradescantia occidentalis, is our beautiful, local native, that grows in the short-grass prairie next to our nursery. It is the only Spiderwort I have grown that is truly drought-tolerant. The 3-petalled purple-blue flowers are accented with gold stamens and are perched in clusters at the ends of 16” stems. The narrow blue-green, grass-like leaves arch obliquely from the stem, and look alert standing in a groundcover.

         The May-June flowers only last a day, and fold up in the noon-day sun, but are produced prolifically for two months or until the ground gets dry. When that happens, this native survivor shrivels and shrinks back into the earth to be strong for the next spring. It self-sows a little, which is a welcome bonus.

         Echinacea tennesseensis, Tennessee Purple Coneflower, is a beautiful and tough non-hybrid, with purple-pink ray flowers and a coppery-orange central cone. The flower petals stand out straight, unlike some coneflowers whose petals droop down. They have a long bloom period from June through August and, curiously, the flowers always face east. The deep taproot and narrow, hairy leaves give this Echinacea more tolerance to dry soils than Echinacea purpurea. It was chosen as a Plant Select Winner for 2013.

         Tennessee Purple Coneflower is tolerant of clay or rocky soils, sun or part shade and moderate watering or dry conditions, especially with some mulch and a bit of shade. Deer are not fond of it, but birds enjoy its seeds and bees and butterflies are attracted to its nectar.

         Allium caeruleum (azureum), the Blue Globe Onion, has heavenly true blue flower globes, an inch or so in diameter. The flowers bloom in May and June on 9”-18” tall, hollow stems. The 3-cornered onion leaves usually have shriveled up by the time the plant flowers. Originally from the Russian steppes, this is a tough plant that can grow in dry, lean soil. Like many onions, if you let the flowers go to seed, you will have many seedlings. A patch two feet in diameter with the stunning blue flowers can be breath-taking, but dead-head, if you don’t want them to be over-taking.

         Lemon Drops is a sweet name for Onosma echioides. This member of the Borage Family is a very attractive and unusual perennial that is well-adapted to Colorado conditions. It sports light yellow, nodding tubular flowers that bloom over a long period. The plant has rough, hairy leaves and grows 10”-14” high and 8”-10” wide. Bees like the flowers and deer do not like the rough leaves. The species name “echioides” means prickly or bristly, and it can be painful to grab the leaves when they have dried in the fall.

 Lemon Drops grows well in gravelly soils, rock gardens and xeriscapes. It does not like constantly wet soils. It is a native of Italy, Greece and Kashmir, and is a favorite of Colorado garden writer and designer Lauren Springer Ogden.

These are a few gems that will be happy with once a week watering if you have restrictions or are determined to cultivate a truly western garden. And they will grace your garden with beauty, bees and butterflies.