Why Must They Suffer?

February brings cold and this week, even Florida won’t escape the freeze. As a gardener, it’s important to stay vigilant. I’ve set my tomato seeds in sprouting trays and will keep them safely indoors during the dip. But what about my poor babies left out in the cold, exposed garden?

They’ll have to be covered. The sensitive ones, anyway. Broccoli and cabbage don’t mind the cold. Peas, either. But my new potatoes I put in ground a week ago? This photo proves how susceptible they are to a wintry blast…

frost bitten potato

Many of my plants are not happy about this cold front. At all. But as I plan my method of protection, I can’t help but wonder, Why do plants suffer during cold snaps?

The answer may surprise you. Like other living forms, plant cells contain water and water can freeze.  According to scientists, during a frost, if water in plant cells freezes, it can damage cell walls.  Why?  Because solid ice takes up more space than the liquid from which it was frozen.  The crystals then rupture the tough cell walls and when the ice melts, any liquid drains out, dehydrating the plant. Soil can also freeze, which threatens plants’ abilities to get nourishment.

Is it true that watering your plants when it gets cold will help protect them?

Yes.  When water from sprinklers turns to ice, the heat released protects the plant from injury. As long as a thin layer of water is present, on the bloom or on the ice, the blossom is protected. This is important. It’s not the layer of ice that provides the protection. It’s the water constantly freezing that keeps the temperature above the critical point. It’s one way citrus growers protect their crops.

orange freeze

Other factors that can affect how damaging a cold spell will be include how long the temperature remains low, whether or not it’s a clear evening versus a nice warm “blanket” of cloud cover, are the plants located in low spots or high across the landscape—even the difference in heat retention between dark soil and light!  Amazing, yes.  But true?

I sure hope so! Temperatures are dropping this week and I’m hoping my black paper will help soak in the sunshine. I’ll keep you posted.