Baby, It's Cold Outside!
Grumpy loves tormenting the poor, frozen souls living up North, who huddle in blankets and parkas each winter staring out of windows at barren tundra. "My camellias are blooming right now," I'll cackle at them. "Let's sit out by the fire with cups of hot chocolate and enjoy that gorgeous sunset!"
Karma, as they say, is a [very bad word rhyming with "witch" that Southern Living will not permit in this column]. Here in central Alabama, the mercury plunged to 14 degrees yesterday and never rose above freezing all day. This can be very bad for certain unprotected plants that die when it gets that cold. How does one prevent this?
First, realize that cold damage to plants is a factor of both how cold it gets and how long the temperature stays there. One night of 20 degrees may damage foliage or flower buds, but may not kill the plant. Three days of temps below freezing may kill it to the ground or kill it entirely. Thus, it pays to know both the immediate and extended forecasts, as well how cold-hardy the plant is. Google it.
Tropical plants, such as orchids, bromeliads, and most plants we use for houseplants, have zero tolerance for freezing weather. If you've left any outside on a freezing night, they're mush right now and not coming back. Let this be a lesson to you. Of course, if you hated that tropical plant but couldn't bring yourself to kill it with your own hands, you're probably feeling pretty good.
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This brings us to what we call semi-tropical plants and tender perennials. Many of these will take a frost or two without lasting damage, if the temperature doesn't get too cold. In Grumpy's case, my potted oleander is surprisingly hardy. It's survived 15 degrees, but that usually kills the flower buds, so it's sitting in my garage until this Arctic blast peters out. Same for my sago palm, which takes temps down to 25 degrees, my angel-wing begonia, my firebush, my bay tree, my elephant's ears, and my orange bells (Tecoma).
The garage gets natural light from windows in the doors, but is unheated and drops into the lower fifties at night. This is exactly what these temporary inhabitants need, so they don't break dormancy before I put them out when temps return to the thirties and forties. That would be disastrous. If a plant must remain indoors for more than two weeks, you probably should leave it there all winter.
What about if tender plants are too big to fit comfortably indoors? Cut them back – it's the only choice. Fortunately, many semi-tropical and tender plants (citrus, olive, hibiscus, flowering maple, etc.) bloom on new growth, so you won't be sacrificing the next year's show or harvest.
Of course, many cold-iffy perennials must be left outside in the ground. You know the drill – some years they come back and some years they don't. To improve their chances, insulate them now by spreading a couple of inches of mulch or fallen leaves over top of them or around the base. Snow is a great insulator, by the way, so if it snows where you are, cut the weather some slack.
By the way, that's my camellia in the photo above and I'm not feeling all that sad. I get to see beautiful camellias blooming every winter and spring. How often do they wear a cloak of snow?