How Do I Protect My Garden From Frost?

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How do I protect my garden from frost?

We are due for some cold nights coming up in WNC and many people are asking what they should do to ensure their plants make it through this (hopefully) last cold snap.

Freeze sensitive plants are tomatoes, squash, begonias, geraniums, cucumbers, eggplant, musk melon, okra, peppers, pumpkins, squash, sweet corn, sweet potato, and tomatoes.

Semi-hardy vegetables are those which can survive repeated light frosts in the 30–32˚F range. These include beets, cabbage, cauliflower, celery, collards, green onions, potatoes, leaf lettuce, mustard, parsnips, radishes, spinach, and swiss chard.

Hardy vegetables such as broccoli, garden peas, spinach, cabbage, and carrots tolerate temperatures down to 28° and lower.

Quick Tips for Protecting Plants

  • Water plants prior to freezing temperatures
  • Trap heat by draping the plant with a frost cloth or sheet NOT plastic tarp. Make sure covers extend all the way down to the ground and are securely held down by bricks or staples. 
  • Mulch roots to minimize temperature fluctuation.
  • Plants in containers should be brought into a garage or other enclosed structure for the night.
  • Open blossoms and blossom buds showing color are more sensitive to cold than other plant parts.
  • Smaller plants such as strawberries or seedlings can be covered with a thick layer of dry leaves or pine straw. 
  • Plants listed as semi-hardy should be covered when temps fall below 30. Crops listed as hardy should be covered when temps are predicted to fall below 25.
  • Don’t give up on cold injured landscape plants. Even if the entire top is frozen, some cold-sensitive woody plants will recover by sprouting from the base or roots. 

Exactly What Is a Hard Freeze?

The National Weather Service issues a hard freeze warning when “widespread temperatures below 28° are expected during the growing season”. This differs from a freeze warning, which is issued when temperatures below freezing are expected during the growing season. These plants are not likely to be seriously damaged this weekend, unless they have recently been transplanted out of a greenhouse without first being hardened off (gradual exposed to cooler temperatures).

Not sure which vegetable crops are considered hardy? Check the list in this NC State Extension fact sheet.

Learn more about the USDA Plant Hardiness Zone Map and lookup zone ratings for anywhere in the US.

**Credit to Charlotte Glenn, State Coordinator, NC State Extension Master Gardener℠ program, for the content of this article. **

Covered plant

Photo : Charlotte Glenn

Garden cloches

Garden cloches made from cut plastic bottles protect plants from frost. Mandy Prowse  CC BY-ND – 4.0

Cool-season vegetables

Figure 1. Cool-season vegetables can tolerate colder temperature