Ask a Local Master Gardener: After harvest, try a cover crop

  • Cover crops like ryegrass, seen here in a cornfield after harvest, can help prepare your garden for spring. TNS/JEFF WHEELER

For the Gazette
Published: 9/20/2019 1:00:21 AM
Modified: 9/20/2019 1:00:09 AM

Q: What should I do with my vegetable garden now? I’m done planting for the year. —J.T., Hadley

A: Many folks are winding down their vegetable gardens now so your question is timely, J.T. One valuable action you can do these next couple weeks to prepare for next spring is to plant a cover crop. You will be so glad you did as it will help make the soil ready to go right from the start next year.

My father used to plant buckwheat in his garden as a cover crop. Some he would till under the following spring and some he would let go to seed. I still remember the first time seeing buckwheat seed. I held their unique, tri-sided shape and deep rich brown color in my young hand in wonder, never having realized seeds could look different from the familiar wheat and rye seeds.

Cover crops are sometimes called green manure crops as their purpose is to naturally add nutrition and organic matter to the soil much as traditional manure does. Instead of eating the crops, gardeners use them to improve soil structure, suppress weeds, and help control winter rain erosion. Cover crops are available as seeds and planting them now, at least four weeks before frost, allows them to get their roots in place and grow a bit before winter. Hardy ones may continue to grow next spring. Come spring, till them under before they mature and their decomposition will inexpensively add wonderful soil benefits.

One kind of cover crop is legumes. Winter peas, hairy vetch, crimson clover, alfalfa, and fava beans are all options here. A wonderful quality of legumes is their nitrogen-fixing nodules. Sounds a bit like something for a race car, doesn’t it? Think of them as nutrition boosters for your plants’ growth engines. They take nitrogen from the air and convert it into a soluble form plants can absorb. Nitrogen is an important fertilizer for plant health, especially for leaves. Yes, plants can create their own fertilizer naturally!

Grasses and cereal crops are another type of cover crop. Oats, annual ryegrass, barley, and winter wheat are all options here. We often think of them as grains, but they are in fact grasses. They have strong, deep roots which can help break up clay soil. Different kinds are good for different soil moisture levels. Research which is best for your type of soil and choose accordingly. Other cover crop options for us here in Zone 5 are buckwheat, brassicas and mustard.

Check the hardiness of the crop you choose so you have a sense of how much it will likely grow before and during early Spring. The hardier the crop, the more growing it will do for you and thus the more organic material it will make. One can combine two crops together, such as a legume with a grain.

Cover crops are a valuable addition to your garden and well worth the effort. Thanks for asking a (local) Master Gardener, J.T.

Have a gardening dilemma? Please send questions, along with your name/initials and community, to the Western Massachusetts Master Gardener Association at One question will be answered per week.

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