Fall is the perfect time to consider improving the soil for spring and summer planting. Should you mulch? Should you cover it with plastic? Instead of allowing the ground to remain bare all winter, consider planting cover crops.
What is a cover crop?
A cover crop is a crop grown to improve the soil, as opposed to a crop grown for harvesting. Cover crops have long been used as a way to preserve the soil from erosion. But cover crops can do more than just prevent erosion. They are an important part of sustainable gardening. Cover crops can improve the soil structure to allow for better water availability, provide beneficial organisms, and add nutrients. Sometimes referred to as “green manure,” cover crops add organic matter into the soil when they are turned back into the ground.
Why should I grow a cover crop?
Having a crop in the ground helps to hold on to the nutrients and soil as well as add additional nutrients. In many gardening zones, there are several months between harvest and planting. This fallow season allows for a lot of runoff due to rain and snowmelt. Not only can the soil wash away, but the increase in rain and snow can also flush out nutrients.
In addition, a cover crop that sprouts and grows quickly can keep out weeds. A bare patch of soil may look tidy, but it’s a welcome invitation to all kinds of weeds.
The roots of a cover crop are doing some other essential work as well. The roots can break up and aerate compacted soil. Some roots dig deep, and others spread all over, creating an ideal garden soil. The roots can also add organic matter and help the growth of microorganisms.
After the roots have had time to work their magic, the top growth can be mowed down and added back into the soil. The simple addition of a cover crop in the fall can help improve even a small backyard garden plot.
What kind of cover crop should I grow?
If you want to add nitrogen and phosphorus to your soil, try a cover crop of Crimson Clover, White Dutch Clover, Austrian Winter Pea, or Hairy Vetch. The bacteria in the roots of legumes form root nodules that take nitrogen from the air and “fix” it into a form of nitrogen that subsequent plants can use. Squash, cabbage, and broccoli are some plants that can appreciate the extra nitrogen.
To slow down erosion while breaking up compacted soil, consider planting Winter Oats or Winter Rye. With their deep and hairy root system, these grains help develop a softer soil that will allow better water penetration. These work especially well in a no-till garden.
If you want to suppress weeds and reduce soil pathogens, try Yellow Mustard, Annual Buckwheat, or Radish Daikon Driller. Studies have shown these cover crops release biotoxic compounds that act as a natural fumigant. Till them into the soil, and in the spring, your garden will be ready for peas, carrots, and potatoes.
How do I plant a cover crop?
The typical time to plant a cover crop is right after harvest. Some varieties are planted in the summer, and some in the fall.
Plant the seeds thickly, not your regular careful spacing, but more like sowing grass seed.
Cover with soil and water well.
For most cover crops, once it sets flower, it is ready to be mowed and turned back into the soil. Depending on the crop, you can either cut it down and turn it all into the ground or take the cuttings and put them into your compost pile. Sometimes it’s too much plant material to turn into the soil, and it will need time to break down in the compost pile.
Allow 2-4 weeks for the cover crop to break down before planting your next crop. The process of decomposing can keep other small seeds from germinating.
Now you know how easy and beneficial a cover crop can be. Give it a try and see what a difference it makes in your garden.
Written by Beverly Laudie
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