In a previous post, we talked about how gardeners can take advantage of the early fall to reinvigorate the microbial life of their soil. Fall is an especially good time to apply volcanic rock dust to the soil because winter rains and snow helps distribute depleted nutrients (like magnesium, calcium, silicon and iron) to plants in plenty of time for spring growth.
Fall is also a good time to sow cover crops. Planted in empty vegetable beds, cover crops help retain nutrients and protect the soil from erosion caused by inclement weather. Cover crops also help keep cool-weather weeds from germinating and can protect against certain pests and diseases.
Cover crops are so beneficial to the soil that some people call it “green manure!”
If you’re thinking about planting cover crops, here are a few suggestions:
1. When planting cover crops, allow at least four weeks before the first anticipated frost so that plants have a chance to become established. Also, protect seeds from hungry birds and squirrels by gently raking them into the soil.
2. Generally speaking, cover crops are low maintenance. Still, they need to be watered during extremely dry weather. They should also be mowed regularly to keep from becoming unmanageable.
3. Dig cover crops back into the soil in the spring. The best time for doing so is when they are flowering, i.e., before they begin to set seed. This provides the soil with valuable organic material beneficial to vegetables and flowers.
So what cover crop is best for you? Consider the needs of your soil as well as the best timing for your geographic region (our suggestions are based on weather in the Pacific Northwest):
Crimson clover – Clover helps build rich soil by fixing nitrogen deficiencies; crimson clover is particularly attractive to beneficial insects (and is nice to look at, too!). Best planted September through October.
Mustard – Many mustard cover crops help suppress diseases and weeds. Mustard crops need 5-6 weeks to establish themselves for best results. They are sensitive to cold temperatures and “winterkill,” i.e., die of exposure, at about 25 F.
Winter peas – As the name suggests, winter peas are quite hardy (they are also known as “field peas”). Like crimson clover, they help fix nitrogen deficiencies. Best planted .eptember through October.
Fava beans – Fava beans help improve soil texture by supporting microbial life. As an added bonus, they’re edible, too (that is, if you like fava beans). Fava beans should be planted in the ground by mid- to late October.
Visit your local extension or knowledgeable nursery for more suggestions on the best cover crops for your area. Come spring, you’ll be glad you went through the effort and your soil will, too.