Protecting Tender Plants from Frost

Article written by Saturday6TM blogger Amy Andrychowicz from Get Busy Gardening

Summer is coming to an end and that means frost is just around the corner for many of us. But frost doesn't have to be the end of the growing season. Tender plants can easily be protected from the first frosts of fall, which can extend the growing season for several more weeks.


Once the threat of frost is near, I usually cover only the tender vegetables. The first few frosts in my area aren't usually killing frosts, and I can handle seeing small amounts of damage on my annuals and tropical plants. But even a light frost can damage tender vegetables enough to make them mushy and inedible.

Tender vegetables that are not frost-hardy include warm weather plants like tomatoes, beans, cucumbers, squash, peppers and some herbs. Cold weather vegetables are frost-hardy and won't be harmed by frost. In fact, many cold-hardy crops actually taste better after being touched by frost. These are plants like broccoli, cauliflower, salad greens, cabbage, kale and Brussels sprouts.

I use old bed sheets to cover my tender plants and protect them from frost. I have also used towels or light blankets when I haven't had enough sheets. But the bed sheets are my favorite; they are lightweight and easier to work with, and they won't weigh down the plant.

The best way to cover plants is to drape the sheets over them and allow the fabric to pool loosely on the ground around the base of the plant. The fabric will protect the plant from frost by holding in the heat that rises from the soil. I use clothespins to hold the sheets closed so they won't blow off if there's wind.

Here are some other tips for protecting plants from frost:

  • Do NOT wrap the plant like a Tootsie Pop sucker, where the fabric only goes over the foliage and then you seal it around the stem or base of the plant - this won't protect the plant very well.
  • Do NOT use plastic to cover the plants. Plastic traps more moisture than fabric and can cause severe damage to the plant if there is a freeze. If you must use plastic, use a support to make a tent over the top of the plant, making sure the plastic doesn't touch any part of the plant.
  • Bring potted plants into a porch, shed or garage overnight. You can also cover them in the same manner as garden plants, but sometimes moving them is easier.
  • Uncover the plants in the morning immediately after the threat of frost has passed. This is usually soon after the sun hits the area in the morning. Leaving the plants covered too long in the sun can cause damage by overheating the plants.
  • The chance of frost is highest early in the morning, just prior to sunrise. It's best to cover your plants right before it gets dark in the evening so they retain the most heat overnight. But, if they don't get covered until after the sun goes down, that's OK too.

Frost can occur any time the temperature drops below 40° F on a clear, windless night. So if it seems like the conditions are just right for frost, take the time to protect your plants; it's better to be safe than sorry.


The Dirt from Troy-Bilt

September/October 2014