Organic gardeners can grow cover crops to enrich the soil.
Nature abhors a vacuum, as any organic gardener can tell you. If a plot reserved for annuals or vegetables lies fallow for any length of time during the growing season, weed seeds carried by animals or the wind soon take advantage of this niche. If you plan to leave your garden plot empty for any duration, you can enrich the soil by planting a cover crop. Sometimes referred to as “green manure,” cover crops provide organic matter to the soil, help bring nutrients to the surface of the soil, and make nitrogen in the air available to garden plants.
You can buy several types of cover crops to enrich the soil in your organic garden. Your choice depends on the length of time you plan to leave the garden plot fallow, the vegetables or flowers you plan to grow, and your soil type.
Alfalfa
Alfalfa, a nitrogen fixer, is a suitable cover crop for large gardens or orchards. It requires a full season to mature. Alfalfa roots deeply, so use it to break up hard soils. You can plant alfalfa in the spring in cold climates, or in the fall in mild climates.
Buckwheat
Like alfalfa, buckwheat requires a full growing season before you can dig it in. Buckwheat doesn’t fix nitrogen, but it does attract bees and predatory hoverflies, so plant it beside an adjacent garden to reap these benefits.
Clover
Red clover is an adaptive cover crop, tolerating shade, acidic soils, and poor drainage. Nitrogen-fixing red clover is low growing, so you can dig it in with a spade rather than a tiller.
Fava Beans
Fava beans not only enrich the soil, they also provide the organic gardener with a crop he can eat at the end of the growing season. Even if you don’t like the taste of fava beans, save some seeds for future cover crop sowings. Fava beans act as nitrogen-fixers, and withstand cold temperatures well.
Mustard
Mustard is a brassica, which means it’s in the same family as cruciferous vegetables like cabbage and Brussels sprouts. Therefore, you shouldn’t use mustard as a cover crop if you plan to plant vegetables in the brassica family in your garden to prevent pests and diseases that attack these plants. Mustard grows quickly, so you can use it as an interim cover crop between summer and fall vegetable crops.
Ryegrass
Ryegrass tolerates cold conditions and grows quickly, so you can plant this as an early spring cover crop before you plant your summer garden. Make sure you plant the annual variety, not the perennial variety used in lawns.
Winter Vetch
You can plant winter vetch, a nitrogen-fixing crop, in the fall and till it under in the spring. This crop can get woody if you allow it to grow too large, so cut it down with a mower as soon as the ground is workable and give it a few days to wilt before you till it into the soil.
Source:
Hamilton, Geoff. Organic Gardening (2004). DK Publishing, New York
