Once you have harvested the last of your veggies, it’s time to put the garden to bed for the winter. You may have heard of “the two C’s,” an easy way to remember the general fall tasks necessary to prepare the vegetable garden for the cold days ahead: clean up the garden and cover the soil.
“Cleanup” is pretty self-explanatory, a commonsense step at the end of the growing season to clear crop debris. As we look at our vegetable gardens right now, we see plants that are pretty well spent; some are dead or dying. Move healthy and clean debris to the compost bin, but if any plants show evidence of disease, remove them from the garden, and do not dispose of them in the compost pile.
About this time, many weeds have grown quite well and are thriving. With shorter days and cooler nights coming on, they are racing to flower and produce seeds to complete their annual life cycle. If you abandon your garden and leave weeds in the ground, their seeds will mature, drop into the soil, and produce many more weeds in the coming years. In fact, weed seeds can live for 5 to 10 years, and some even longer. Certain weeds will continue to grow despite winter temperatures. Moreover, weeds left in your garden provide places where pests and plant diseases can hide and survive the winter. The effort you put into removing weeds today will pay off in the future.
After you have cleaned up the garden, it’s time to cover the soil, the second of the two C’s. Leaving your soil bare will lead to at least two outcomes you want to avoid: weed growth and soil erosion. As noted, there are quite a few weeds that will grow well in our Virginia winters. Plus, harsh winter wind and rainfall will sweep away bare topsoil and helpful organisms while sending sediment-laden runoff into nearby streams. The result will be poor soil health and poor water quality.
Follow the four basic principles for maintaining and improving soil health identified by the USDA Natural Resources Conservation Service:
- Keep the soil covered as much as possible,
- Disturb the soil as little as possible, and
- Keep plants growing throughout the year to feed the soil—a.k.a. “living roots.
- Diversify crop rotations including cover crops
One option is to cover your vegetable garden in the winter with dead plant material, such as a thick layer of straw or leaves. This will protect the soil from the scouring effects of rainfall and prevent weed growth.
An even better option is to plant winter cover crops. This will not only reduce soil erosion and suppress weeds; it will also improve water infiltration and soil tilth—the soil structure that helps plants grow. Cover crops also provide large amounts of organic matter that will keep the soil biologically active by providing a food source for beneficial organisms. Insects, earthworms and different types of microorganisms feed on decomposing matter in the soil, converting rotting material to available nutrients.
Learn more about preparing your garden for winter in our latest issue of PMG’s newsletter, The Garden Shed.
WHAT ARE COVER CROPS?
Cover crops are planted in an unused garden space and then removed when it’s time to plant edible crops. Essentially, they are placeholders, keeping the soil biologically active between growing seasons.
It is good to mix several kinds of cover crops to promote diversity. They typically fall into three categories:
- Annual grasses such as winter rye or winter wheat. Their massive root systems will break up tight, clay soil, and will improve soil structure by preventing compaction and erosion.
- Legumes. Clovers, alfalfa, peas and vetch are all common legume cover crops. The most notable feature of legumes is that they work with certain soil bacteria to convert atmospheric nitrogen into nitrogen in the soil that can be absorbed by plant roots. This is known as nitrogen fixation. Crimson clover fixes up to 200 pounds of nitrogen per acre and sports striking crimson blossoms in the spring that the bees love.
- Non-Legume/Broadleaves, such as tillage radishes. These plants have extra-long taproots that break up and aerate the clay soil in addition to drawing up nutrients for future crops.
In summary, cover crops can provide many benefits to soil health, especially when used in combination.
The best time to plant cover crops in our area is from September to mid-November, depending on the weather. In the spring you cut the crop down with a scythe or string trimmer before it goes to seed. Allow 10 to 14 days for the roots to start to break down, and then plant food crops directly.
Recently, the Piedmont Master Gardeners teamed up with one of our community garden partners, the International Rescue Committee’s New Roots garden program, to demonstrate the importance of fall cleanup and coverup and the benefits of protecting the soil with a variety of winter cover crops. Volunteers then helped mix a “cocktail” of cover crop seeds, including annual rye grass, crimson clover and tillage radishes, and planted them into freshly prepared soil.
Once you have cleaned up and covered up your soil, both you and your garden can take a well-deserved rest. It’s a great time to read some garden books, reflect on what you achieved this past season, and start planning for the next. Read this for more fall gardening possibilities.
