Colorado Mountain Gardener: 8 Ways Cover Crops Can Improve Your Garden

By Patti O’Neal, Jefferson County Extension Horticulture and Urban Food Systems

Cover cropping, a strategy also known as green manure, has been practiced by gardeners and farmers the world over for over 10,000 years. This organic restoration practice can boost your garden noticeably the very first year you incorporate it into your own best management practices and the improvements increase even more each year as their effects accumulate. These crops are easy to use, do not need much care beyond watering and a mowing/cutting or two and provide tremendous advantages to the garden and gardener.

Cover crops are plants that are considered soil builders. Here are 8 sometimes overlooked ways that cover crops build the soil productivity in your garden:

· Provides Beneficial insect habitat – pollinators, honeybees, beneficial predator insects will all enjoy the nectar as well as the shelter these crops can provide at every season you use them.

· Smothers weeds and suppresses their seed from germinating as well. They provide a dense mat to keep the light from reaching the seeds.

· Better, more complete soil tillage than any mechanical method. These crops improve soil structure, allowing more air and water penetration. They can break up soil compaction, loosen tight, hard, or heavy soils and create good tilth.

· Provides shade for the soil for cooler root temperatures, less moisture losses during hot weather.

· Acts as a living mulch when established between vegetable rows.

· Increases organic matter in the soil while feeding the microbes, beneficial bacteria, fungi, and earthworms living in the soil.

· Conserves soil moisture both at the surface of the soil and in the critical root zone. The extensive root systems conserve soil by reducing erosion from rain by slowing water flow across and through the soil. The living foliage can also buffer wind effects.

· Fixes nitrogen from the air while recycling nutrients, preventing their run-off and leaching from the root zone, simultaneously bringing up deeper nutrients to plant roots that are usually unavailable.

Use seasonally appropriate cover crops. Legumes, vetches, rye, and buckwheat are all excellent cover crop plants. Like all plants, each cover crop germinates and flourishes best in certain seasons. Most reputable seed companies will sell individual crop packets or recommended mixes appropriate for specific season plantings. Some cover crop seeds are available locally, but seed catalogues have the widest range and generally provide good advice and instruction on using them.

If you are letting a bed or area of your garden go fallow for a season, this thousands year old practice of planting a cover crop can help to replenish the biological community of your soil below while providing nectar as well as shelter for pollinators and beneficials above. Here are a couple of tips to help you be the most successful with a green manure crop.

Allow your crop to flower but watch carefully and do not let it go to seed or you will be battling weeds of a different sort in the months to come.

Flowering red clover

If you plant early enough in the season you can get one or maybe even two mowing’s in (If you garden in raised beds, a weed whacker works great for this) forcing the root material into overdrive to produce another above ground crop. This action forces the root system further into the soil to depositing additional nutrients while continuing to improve tilth, bringing formerly unavailable nutrients up to the plant root zone.

After your final mowing, fork the remainder of the material under so the microbes and arthropods you have encouraged can break it all down completely to become plant available nutrients. Be sure and do this at least a month to six weeks before your intended planting date for this bed. Otherwise, the increased microbial activity will compete with the root establishment of new plants or can even disrupt germination of seeds. You do not want to spoil all the good work you have done.