Flood Recovery for the Garden

Flood recovery is not a problem most of us have had to deal with before so we can only try to solve the problems individually and make adjustments in the future.

The main problems seem to be: 1) Soil washed away-erosion 2) Soil dumped on top of plants, trees and existing soil 3) Plants washed away

4) Weed seeds deposited on the soil 5) manure and sewage and unknown contaminants deposited on the land

         Soil washed away: Soil can be hauled in or the remaining soil can be rejuvenated. Most topsoil for sale in Colorado is mostly screened clay, so if you have soil hauled in, unless you are filling deep holes, order Planter’s Mix that has at least 30% compost. If you are rebuilding the remaining soil where the topsoil was washed away, cover the soil with 2” of landscape-waste compost (composted manure is fine if only 1” is put down or if there are no plants to burn, 2” is good). Rototill or dig this into the soil along with an organic fertilizer (organic is longer lasting and contains important micronutrients). Or plant a cover crop and till it in at the proper time.

         If soil was washed off tree roots, cover them with no more than 2” of soil because the roots need oxygen, and perhaps 2” of a fine wood chip mulch that will break down more quickly and add to the organic matter of the soil.

         Soil dumped on top of plants, trees and soil: As soon as possible, remove soil that is piled on top of tree roots if it is more than 2” deep. If too much soil covers the roots, trees can decline or die. If the soil is over grass only, the grass can grow up through 1”-2” of soil and some people say grass can grow up through 5” of silty-sandy soil.

         Soil on top of plants must be removed immediately or it may already too late to save them. After shoveling close to the plant, it is easier to use a hose to wash (or blast) off layers of mud. A layer of silty-sandy soil might actually be beneficial to let water through which will be held by the clay layer below, and it may provide better drainage than your original clay soil and therefore be easier to grow drought-tolerant plants. You will probably want to add some compost and fertilizer to these deposited soils. It could also be a good idea to get a soil test.

         Plants washed away: If most of your soil is left intact, just replant. At the end of this article there is information on where to find a list of plants that are good frontier plants to establish on poor soils or in exposed, rugged sites. The list includes plants with tenacious root systems that prevent erosion and resist washing away.

         Weed seeds deposited: Many plants will come up from seeds deposited by the flood water, and in the mud. Many of these volunteers will be weeds, but some near the foothills or open spaces will be natives. There can be several approaches: 1) let everything grow until it gets big enough to identify and cut down the undesirables before they flower and go to seed. They can be composted or left on the ground for mulch 2) plant no seeds and plant container shrubs, trees and perennials, then sow the area with Corn Gluten which will prevent all seeds from developing 3) weed everything, water and let the seedlings come up and weed again (maybe even a third time), then plant grass seed, cover crops or what have you.

         Manure, sewage and other contaminants deposited on your land: Nature is a wonderful rebuilder/recycler all by herself, but she needs time to perform her magic of turning wastes into fertilizer. We humans can speed up the process considerably by feeding the existing microorganisms their favorite foods-carbon and natural nitrogen (plant wastes and animal wastes). And we can also inoculate our soils with beneficial bacteria, beneficial fungi and mycorrhizae to speed up the breakdown of wastes and to colonize the roots of plants. This is especially important where the topsoil was washed away along with the soil life.

         The Biodynamic community has long relied on Pfeiffer’s Field Spray which is a combination of 55 selected microorganisms to rapidly breakdown organic matter like raw compost and cover crops. Also effective are compost tea, a biologically active compost spread over the ground and scratched in, and there are other microbial products that can speed up the composting process and purify organic contaminants.

In my personal experience, I have seen how the composting process, rich with soil microorganisms can even break down pesticides.

         Rebuilding soil and preventing erosion can be accomplished with planting seed mixes of grasses that are adapted to our conditions. Mountain conditions are different than Plains conditions are require different grasses. For the Foothills, Lynn Reidel, from Boulder Open Space and Mountain Parks, recommended this mix: Western Wheatgrass, Thickspike Wheatgrass, Slender Wheatgrass, Green Needlegrass, Sideoats Grama, Blue Grama, Little Bluestem and Buffalograss

Plants to establish where the topsoil was washed away or to prevent erosion

NATIVES:

Amelanchier alnifolia-Serviceberry

Artemisia filifolia-Sand Sage

Artemisia frigida-Fringed Sage

Artemisia ludoviciana-Silver King Sage

Artemisia tridentata-Big Sage

Cercocarpus montanus-Mountain Mahogany

Cercocarpus ledifolius-Curlleaf Mt. Mahogany

Cornus sericea-Red Twig Dogwood

Ericameria-both Tall and Dwarf Rabbitbrush

Mahonia repens-Creeping Mahonia

Populus tremuloides- Aspen

Prunus Americana- Wild Plum

Prunus virginiana- Chokecherry

Quercus gambelii-Gambel Oak

Quercus undulata-Wavyleaf Oak

Rhus glabra cismontana– Smooth Sumac

Rhus trilobata – Threeleaf Sumac

Ribes aureum-Golden Current

Ribes cereum-

Rosa acicularis

Rosa arkansana

Rosa woodsii-Wood’s Rose

Rubus deliciosus- Boulder Raspberry

Salix irrorata-Bluestem Willow

Shepherdia argentea- Buffaloberry

Symphoricarpus – Snowberry

Achillea lanulosa-Native Yarrow

Asclepias speciosa-Common Milkweed

Asclepias tuberosa-Butterfly Weed

Aster laevis-Smooth Aster(and other asters)

Eriogonum many species

Eriogonum umbellatum-Sulphur Flower

Fragaria americana-Wild Strawberry

Geranium viscossimum-Sticky Geranium

Helianthus pumilis-Dwarf Sunflower

Helianthus salicifolius-Willowleaf Sunflower

Heterotheca villosa-

Iris missouriensis-Blue Flag Iris

Linum lewisii-Blue Flax

Mirabilis multiflora-Desert Four O’Clock

Oenothera  caespitosa-White Evening Primrose

Oenothera missouriensis-Missouri Evening Primrose

Rudbeckia hirta-Blackeyed Susan

Solidago nana-Dwarf Goldenrod

Solidago rigida-Stiff Goldenrod

Thermopsis- Golden Banner

NON-NATIVES:

Achillea millefolium-creeping yarrow

Anacyclus depressus-Atlas Daisy

Chives and Garlic Chives and Garlic

Daylilies

Geraniums-many varieties

Many Asters

Many Creeping Veronicas

Many Sedums

Potentilla verna

Prunella vulgaris-Self Heal

Raspberries

Red Valerian

Tanacetum niveum

Various mints

Vinca major and minor-Periwinkle

Apples if not soggy soil

Buddlea alternifolia-Silver Butterfly Bush

Dwarf Flowering Almond-Prunus tenella

Lilacs

May Day Tree-Prunus padus

Nanking Cherry

Peking Cotoneaster

Siberian Peashrub