The majority of popular houseplants are natives of tropical or subtropical climates. That means they aren't fond of cold weather. If introduced to lower temperatures gradually, most adapt nicely. But if, all of a sudden, they find themselves chilled, the results aren't pretty.
This can happen several ways:
1. You take a winter vacation and turn the thermostat back to 55 degrees F., or lower.
2. The heat goes off during a winter storm.
3. Plants are left on windowsills – often behind sheer curtains – when temperatures drop far below freezing.
4. You take an indoor plant outdoors during a "warm spell" in January or February, when 50 degrees F. feels like a heat wave to you (but not to a tropical plant).
So what can you do to prevent damage to your plants from the chill?
1. Set your thermostat no lower than 60 degrees F in winter, if possible.If you can't, gather all houseplants in the warmest room in your house -- or the one that's warmed most by the sun. Grow lights may also provide some warmth.
2. Ask someone to walk through your house each day while you're gone. If the power goes off or the furnace fails, he or she can try to get someone in to fix the problem quickly.
3. If you can, remove houseplants from windowsills when temperatures dip below freezing, particularly if you don't have double-paned or storm windows and/or you can feel cold wind blowing right through. Other options include placing cardboard or Bubble Wrap between the glass and the plants, pulling down the shade between the window and the plants, and keeping curtains or draperies open at night.
4. Don't take houseplants outdoors, even temporarily, until after your spring frost-free date. Even if the plant doesn't get too cold, it will receive way too much sun on its "day out" and then be thrust back into much lower light levels, which will require adjusting (and probably some yellowing and dropped leaves). In mild climates, you may find that if you leave plants outdoors when you're gone, one night the temperatures dipped much too low for the plants' comfort.
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