As space frees up in the in the autumn vegetable garden, it’s time to make plans for how your beds will spend the winter. Exposed soil suffers from wind and water erosion, and heavy rain can leave it compacted. Your soil deserves better, but there is no one-size-fits-all method for protecting vegetable beds in winter. Rather, you can choose between mulches, cover crops or green manures based on the needs of each bed, while factoring in your planting plans for next year.
Helping Sick Soil
My tomatoes produce beautiful crops, but they always end the season as a diseased mess. Two forms of blight and Septoria leaf spot infect the plants, which shed a lot of diseased leaves before I pull them out. To clean things up I gather up the old mulch and compost it, and then sow a quick cover crop of mustard, which has a sanitizing effect on soil when the fresh greens are chopped into the soil. Then I follow up with a cushiony mulch of chopped leaves.
Mulch to Reduce Weeds
In terribly weedy beds, the best option might be a winter mulch of straw or rotted hay, spread over the undisturbed soil. Weed seeds left on the soil’s surface will be right where crickets, ground beetles, ants, earthworms, slugs, and field mice expect to find them. An active predator community under an insulating mulch may stay active all winter, plus the mulch will contribute to the rotting of many weed seeds.
This is the method I’m using in the row where I grew sweet corn and its robust crop of companion weeds. After pulling up the corn and cutting down the weeds, I mulched it with some seedy rye straw (at least it’s organic). The bed will function as a seed-eater’s winter resort, with plenty of cover for these important beneficial life forms.
Soil Building Winter Cover Crops
From buckwheat to winter peas, you will find many cover crop choices listed in the GrowVeg Plant Guides. But finding a good fit between your garden and winter cover crops may take some trial and error, because cover crops that work in one garden may not be worthwhile in another. Be ready to experiment as you look for winter cover crop plants that thrive in your site and soil.
Over the years I have found that a mixture of cover crop species, fine-tuned to my climate, is fun and rewarding to grow provided I get it planted in September, when the soil is still warm. My winter cover crop mixture is comprised of crimson clover with lesser amounts of hardy grains, winter peas, vetch, and annual rye mixed in. I get a better stand than I would using only crimson clover, and in mild years the planting never loses its vibrant green color.
I also love using oats and daikon radishes as a winter cover crop, because the plants do winterkill and then rot in place, leaving the bed ready to work in early spring. But as with other soil-building cover crops, early fall planting is critical to success. Winter hardy grains are less picky about soil temperatures, and good old cereal rye will germinate in soil that’s become chilly to the touch.
Blankets for Raised Beds
What about beds that are vacated so late that there is no time to sow a cover crop? You can always start cover crop plants in plug trays and pop them into the ground when it becomes available, or circle back to mulch. You could cover the beds with wet newspapers covered with compost or chopped leaves, and then secure the whole thing with burlap or another type of cloth that looks attractive and holds the mulch in place. This is a great use for old blankets or thrift store bedspreads, which can look quite prim when tucked in at the edges. Burlap (hessian) or burlap bags (cheap or free from coffee roasters) appear more rustic, but burlap is a fast and easy way to protect vegetable beds in winter.
It’s a coming trend to protect vegetable beds in winter with biodegradable seed blankets or ‘felts’ made of wood, straw, jute or (coming soon) hemp. Widely used in hydroponics, these new plant-based mats are perfect for cutting to size for raised beds. The tougher materials can be reused a second year when rolled up and stored dry through the summer months, like winter carpets for the vegetable garden.