Planting Cover Crops
How to Protect and Improve Your Soil in the Off Season
Whether you're looking to protect your soil throughout the winter or control weed growth throughout the summer, cover crops can help you maintain a nutrient-rich and bountiful garden.
You can choose all sorts of plants to grow as cover crops. Some of them you might have heard of, such as winter rye. Others might be completely unfamiliar – hairy vetch, anyone?
No matter which plants you choose, growing them is as easy as tending any other plant in your garden, and blending them into your soil can be done with a cultivator or tiller.
Benefits of Cover Crops
Cover crops are sometimes called "green manure" or "living mulch." So what do they do that makes them so good for your garden?
- Add nitrogen
- Regulate soil moisture
- Reduce weed growth
Nitrogen is a component that's key to plant growth. The plants that make the best cover crops work together with soil bacteria to draw nitrogen out of the atmosphere and convert it into a form that the plants can use. After your cover crops die and decompose, their nitrogen returns to the soil, where other plants can absorb it and thrive.
But nitrogen isn't the only ingredient for healthy growth that cover crops can help with. They also make sure your garden has the right amount of moisture. During the wet season, they deliver rainwater into the topsoil where your crops' roots can absorb it. During the dry season, they provide a root system and ground cover to prevent erosion.
Finally, cover crops are excellent for controlling weed growth. Instead of having large, out-of-control weeds sprouting up in your garden, you can fill your garden spaces with a less intrusive and more manageable cover crop that improves the quality of your soil.
Choosing a Cover Crop
The cover crop you choose should depend upon the growing conditions in your geographic area each season and your desired results.
In areas with a cold climate, such as the northern United States, you have the option of growing a cover crop like oilseed radish that will die off before winter and provide some soil protection and a lot of nitrogen as it slowly decomposes.
However, most cool-climate farmers and gardeners prefer a hardy crop that's able to tough out winter weather, so that its roots will hold in place and prevent soil erosion throughout the season. Three cold-weather cover crops are especially common:
- Winter rye
- Hairy vetch
- Crimson clover
Gardeners in southern states and other areas with warm, mild climates can choose cover crops that are great for their soil but aren't as hardy against the winter cold:
- Common vetch
- Yellow lupine
Crops like these will grow alongside your main crops, which is why many of them earn names like green manure (because they actively add nutrients to the soil) or living mulch (because they prevent weed growth and soil erosion as they grow).
Caring for Cover Crops
Most cover crops are relatively easy to manage. They don't require a lot of watering, but they should be monitored for healthy growth.
When your cover crop becomes overgrown, it's a good idea to mow it. Leave it long enough to serve its purpose, but trim it to keep it under control and make sure its growth doesn't interfere with the growth of your main crops. Some gardeners suggest trimming your cover crops shortly after they've begun to bloom.
If your cover crops are struggling, especially during warm or dry periods, consider adding compost to your garden. Not only will compost help maintain consistent moisture and temperature in your soil; it also will release nutrients slowly enough to help your crops grow without encouraging fast-growing weeds.
Tilling Your Cover Crop
Just before the start of a new growing season, it will be time to till your cover crop into the soil.
If your cover crop died back in autumn and had been serving as ground cover throughout the winter, the leftover material will blend easily into your garden soil when you break it up with your garden tiller.
However, if your cover crop survived the winter, you'll have a couple of extra steps to take:
- Mow your cover crop extremely short
- Let the clippings and roots dry and decompose for several days
- Till your crop into your soil after it has dried
Tilling your cover crop will allow the decomposing matter to release nitrogen into the soil while also providing the soil with other nutrients.
After you've tilled your soil, wait several weeks before sowing your primary crop seeds. This waiting period will allow enough nitrogen to return to the soil for your new seeds to take root.
Once you've waited a few weeks, you can proceed with planting your new crops and starting the growing cycle again.