Falling Temperatures

April 6, 2007

I received an e-mail today from a gardener in North Carolina who shared some concerns that many of us may have regarding the cold weather that is forecast to strike our gardens over the next few days:

Weather Worries in the Garden

“I live in N.C. and we planted our garden two weeks ago. Normally we don’t have any more frost. The next four days the temps here will be around freezing and below at night.”

“Do we uncover our garden during the day? Do we water it during the day or will that cause it to freeze? I am sure I was told before that when temps are dropping to give plenty of water and that will help to prevent a plant from freezing.”

“Is this correct? My husband and I have a disagreement on this. Our plants of course are very small and fragile. Please help!”

Sheltering Cold Hardy Vegetable Plants

Hi Robin, we’re in the same situation here in the north with temperatures expected to dip as low as twenty-seven degrees over the next couple of nights. You didn’t mention what types of plants you have out in the garden and that’s going to make a big difference.

If you’re talking about frost hardy plants like kale, collards, cabbage, broccoli, kohlrabi, and other leafy greens that have been properly hardened off there shouldn’t be cause for much alarm.

Even without protection cold hardy vegetable transplants can easily withstand a frost and light freezes without suffering damage. The only vegetable transplants that I have in the garden right now are a small number of lettuces, cole crops, and globe artichokes, so I plan to gamble and not bother covering them this weekend.

To play it safe they could be covered with heavyweight floating row covers or plastic to provide some extra insulation against this unexpected cold snap. You definitely should remove the plastic covers during the day after the sun warms the air.

Floating row covers and vented materials can remain in place throughout the day but don’t offer as much protection against the cold. If you use sheets of plastic to cover the garden try to prop the material up with wire hoops or even cages to keep the material up off of the plants if possible.

Protecting Frost Tender Transplants

For frost tender plants such as tomatoes, peppers, cucumbers, and melons caught out in the garden the situation is much more delicate. Just a touch of frost will destroy these crops if they are exposed. The best thing that you can do is to cover them and pray that temperatures don’t fall too drastically.

You can cover the plants with whatever materials are available. Plastic tarps, blankets, five gallon buckets, flower pots, portable cold frames, etc. Improvise by cutting the tops off of liter soda bottles and plastic gallon jugs and insert them over your plants in the evening and remove them the following morning.

For more ideas read the entry about frost warnings that I wrote last year. I discussed methods for protecting cold sensitive plants from frost, which is much easier than handling the freezing conditions that we are currently faced with, but some of the information is still relevant.

Don’t forget to uncover your plants during the day, but I wouldn’t worry about trying to water them to prevent freezing at this point. Some gardeners recommend watering the garden in the morning before temperatures drop to increase the moisture content of the soil which will hold more warmth in the ground. That way the plants themselves dry off before the freeze sets in overnight.

Good luck with all the gardens and plants out there, hopefully temperatures won’t fall too low and things warm back up quickly after this weekend! If you have more ideas to help protect plants from the cold please leave a comment below. Thanks.

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