Some plants just aren’t cut out for cold weather, but a surprising number of perennials are perfectly capable of surviving a frigid winter—at least with the right protection. As the temperatures start to cool down, it’s important to take a few simple steps to insulate your plants and soil from the cold season ahead. Here’s how.
Insulate plants with mulch
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The best way to protect plant roots from freezing temperatures is good old mulch. Blanketing the ground around your plants with mulch keeps root systems nice and warm and, as a bonus, can discourage weed growth over the winter.
You can buy bags of the stuff at hardware or garden supply stores, but there’s no need to: Any chunky mixture of dry-ish, decaying (but not rotting) organic matter can be used as mulch: Think straw, wood chips, dead leaves, pine needles, yard trimmings, or even early-stage compost. Certain man-made materials, like rubber and plastic, can also work, particularly if weed growth is your primary concern.
If you’ve mulched extensively and are still nervous about leaving your favorite perennials out in the elements, the Oregon State University extension program has a neat trick for insulating plants that you “especially prize:”
Assemble a tomato cage (the square, folding types are best) around it. Wrap burlap around the outside of the cage and secure with bungee cords. Fill with straw or leaves.
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Building special little plant cocoons is more work than strategic mulching, but it’s a great choice for plants you really don’t want to see damaged.
Protect bare soil with compost and a blanket
Believe it or not, bare soil also needs protection from winter weather, too. Freeze-thaw cycles kill beneficial critters and microorganisms, and can even cause erosion—not what you want to deal with come spring.
Compost is the perfect solution to this problem because it insulates the soil and provides it with tons of nutrients. The UK Soil Association recommends spreading a few inches of it directly on bare soil and empty garden plots, then covering everything with something sturdy but breathable, like an old blanket. When the weather warms back up, uncover the compost and leave it alone for a few days to “breathe,” then dig around in the dirt to evenly distribute all the good stuff.
Whether you’re protecting plants, soil, or a little of both, remember to remove any insulation before growing season begins. The timing will vary depending on your location and the type of plant—or soil—but a good rule of thumb is to start de-winterizing when spring temperatures start up for real. If you’re not sure when that is, your state university’s extension program should have specific guidance.