Cover Crops: Green Gold For The Garden
Oct 10th, 2012 | By Esther | Category: Food, Gardening, Top Headline | Print This Article
I’m always looking for ways to improve the sandy, dry soil in my Colorado garden. I’ve hauled countless loads of manure from a nearby alpaca farm, and I keep a compost heap humming at the edge of the garden. A few years ago, I added cover crop rotation to my list of soil-building tricks. It’s one of the least expensive and simplest methods for adding organic matter to the soil. If you haven’t tried cover crops in your vegetable garden, this might be the year to try it. Cover crops offer several benefits:
- Cover crops prevent soil erosion during the winter months when the garden lays bare. If you live in a windy area like mine, erosion is no small matter. In one winter, I can easily lose ½ inch or more of topsoil.
- Flowering cover crops like clover encourage beneficial insects to come to your garden. The adults lay their eggs in the soil and around the garden so you’ll have an army of pest-eating troops the following summer.
- Cover crops prevent weed growth and loosen the soil with their deep roots.
- Through the decomposition process, cover crops add nutrients to the soil, encourage microbe growth, and improve the soil’s texture. Whether you have sandy soil like mine or heavy clay soil, adding organic material is the way to improve it.
- Some cover crops actually inhibit weed growth.
How To Plant Cover Crops
Plant cover crops in the fall because they need at least four weeks to grow before cold weather zaps them. Clear all the garden debris from the soil and compost or discard it. Add some manure or compost to the soil and till it to a depth of six inches. Spread the seed fairly thickly to form a dense mat. If you live in a dry climate like mine, you’ll have to irrigate a bit to keep the seed bed moist. Once the plants emerge, reduce or eliminate watering.
Till the cover crops under in the spring—at least three to six weeks before you plant crops. I tend to wait as long as I can so the crops keep weeds down, but you want the crops to decompose before planting time. Definitely till them under before they go to seed or you’ll have hairy vetch and rye growing among your vegetables.
How To Choose Cover Crops
When choosing cover crops, you’ll need to take several factors into account. First, how long does the crop take to grow? If you live in a short season area, you want a crop, such as annual rye grass, that grows very quickly. Winter wheat, rye, and oats also establish quickly.
You’ll also want to think about how easy the crop is to incorporate into the soil in the spring. Annual crops like annual rye grass and oats are fairly simple to dig under. Perennial rye grass, on the other hand, has deep roots, and grows back.
Consider also your goals in planting cover crops. If you simply want to add organic matter and prevent soil erosion, a grass will do the trick. To add nitrogen to the soil, though, plant a crop from the legume family like alfalfa or hairy vetch. Or better yet, plant a combination of both types.
Then, think about any special soil considerations. Winter wheat doesn’t grow well in soggy or acidic soils. Oats need very good drainage, but tolerate a lower soil pH than some crops.
If you’ve got a garden area with very poor soil, you might want to let it sit fallow for one season and cover it with summer-growing cover crops like clover. Plow the crop under in the fall or let it sit over the winter and plow in the spring.
Below is a brief description of the most common types of cover crops:
Alfalfa is a legume cover crop that fixes nitrogen in the soil. This hardy plant needs warm, moist soils to germinate. Plant it in spring through late summer.
Austrian Peas are a legume crop that grows quickly and may become weedy. Sow it in fall and turn it under in the spring.
Barley is a grain crop that tolerates drought and alkaline soils. Plant it in fall or spring.
Crimson Clover is a legume that fixes nitrogen in the soil. It prefers moist, alkaline soils and is less winter hardy than white clover. Plant it by early fall or in the spring.
Fava Beans are a nitrogen-fixing legume that grow quickly and tolerate cool climates and a variety of soil conditions. Treat fava beans with nitrogen-fixing bacteria.
Oats are a cereal grain, suitable for improving soil texture. Plant it spring or early fall. Not as winter hardy as some.
Annual Rye is a very hardy grain crop, making it an ideal choice if you have a long growing season followed by a quick freeze. Sow it in late fall and till it under in the spring.
Hairy Vetch is another legume crop that fixes nitrogen. It can become weedy so till it under long before it goes to seed.
Winter Wheat is similar to barley in its growing needs. Plant it in fall to turn under in the spring.
Where Do I Buy Cover Crops?
You’re local nursery may sell cover crop seed, although the least expensive place to shop is a farm store. If you don’t have one in your area, look online. Most farm stores and online sources sell cover crop seeds in bulk for farmers, which may be a lot more than you need. Try going in with a few neighbors and split the cost of the seeds. You’ll get high quality seeds at a fraction of what you’ll spend at the nursery.
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