When it comes to gardening, the soil is your most valuable asset. But a season of growing food for your own consumption robs the soil of valuable nutrients. Soil left bare after harvest is subject to erosion, compaction and weed invasion. Many of these problems can be solved by planting crops in late summer to early fall – not for consumption, but for their value in protecting the soil from erosion and adding back lost nutrients consumed by “hungry plants” such as tomatoes, cucumbers and corn.
Cover crops that do well our in region include grasses such as alfalfa, annual ryegrass and winter rye. They are hardy enough to survive our valley winters when planted in the fall and allowed to grow through the winter. In spring these plants are turned back into the soil before they flower, but definitely before they go to seed. This ensures that you won’t have unwanted seeds germinating at a time when you are growing your food crops. Once tilled in, these plants improve the soil’s texture and water-holding capacity by adding organic matter. Their roots loosen up compacted soils from last season’s weeding and harvesting activities. Also, their presence through the winter shades the soil and prevents germination of many perennial and winter annual weed seeds.
Legume plants such as alfalfa, clover and vetch also act as cover crops and are often planted with grasses to add back nitrogen depleted by last season’s crop. Legumes are nitrogen-fixing plants, which form a relationship with soil bacteria that attach themselves to plant roots. These bacteria “fix” nitrogen from the air. This fixed nitrogen gets into the plants and is ultimately returned to the soil. Cover crops used for the purpose of adding nutrients to soil are call “green manures.” Whether cover crops or green manures, these winter plantings have the added value of attracting beneficial insects to your garden when they flower, and improving the soil environment by making it more hospitable to earthworms and microorganisms that break down organic matter.
This fall, University of Nevada Cooperative Extension is offering a new series of classes to the public called “Grow Your Own.” These classes will offer the beginner and seasoned gardener alike tips for successful edible gardening in Nevada’s harsh climate. Weekly classes start September 20, and will be held in Reno and video conferenced to Cooperative Extension offices across the state. Information on efficient ways to grow produce in your own backyard will be provided, including details on how to effectively plant and harvest cover and green manure crops.
Previously known only to large-scale agriculture, cover cropping is well adapted to smaller scale backyard gardens. Crops are usually seeded in to empty spaces left after summer harvest or planted between rows of second season vegetables such as spinach, lettuce, peas, carrots and beets. If winters are especially severe in your area, you can even plant green manure crops in early spring, when they can prepare the soil for your summer vegetable garden. These crops are either cut back and composted, or turned into the soil while they are still green and growing to prepare the soil for your warm season vegetables.
The time to think about cover cropping is now, before the soil freezes so seeds have a chance to germinate and take root. Feed your soil, not your plants, by planting cover crops for a bountiful garden next year.
Heidi Kratsch is the Area Horticulture Specialist with the University of Nevada Cooperative Extension. She can be reached at firstname.lastname@example.org. For more information on the Grow Your Own class series contact your local Cooperative Extension office. In Reno, call 775-784-4848. For answers to general horticulture questions, contact our university-trained master gardeners at 775-336-0256.