The first week in January was cold here in South Florida, by just about anybody's standards. Tropical plants and orchids hate this weather even more than we do.
Although crotons, hibiscus, ginger and any number of tropical plants don't like cold temperatures, and will often drop leaves, orchids are by far the most sensitive.
The most obvious solution for protecting potted orchids is simply to bring them into the house. However, if you've ever tried this, you have probably spent the rest of the week going after ants and lizards that came in with your plants and cleaning up spilled potting media.
Garages, while typically not heated in South Florida, can still make good enough shelters because they do protect from wind and are undoubtedly warmer than the outdoors. And if you have some sunlight coming in, orchids can stay put for a few days.
The University of Florida, in a publication called Tips for Growing Orchids in South Florida, by Robert J. Black (edis.ifas.ufl.edu/ep017), also advises that tree canopies elevate minimum night temperatures by reducing radiant heat loss from the ground. Potted plants that are bunched together also tend to lose less heat.
If you can't move them, then you really should come up with some kind of Plan B, since most orchids get pretty unhappy with temperatures below 50, much less a freeze. Every year I say that I am subscribing to a "survival of the fittest theory," but at the last minute I usually break down and do something.
"Water is the only feasible source of heat available to plants grown in the open, under trees, in shade houses or on patios in South Florida," writes Martin Motes, a well-known South Florida orchid expert, in his book Florida Orchid Growing Month by Month. He recommends running your irrigation system or an oscillating sprinkler from dusk until dawn to protect orchids on frosty nights.
For most of us hobbyists with a couple dozen orchids, this isn't practical, especially with the current water restrictions.
Though not as effective as the all night shower, Black suggests that watering plants thoroughly early in the day when a freeze is forecast can help. His article advises that "a well-watered soil will absorb more solar radiation than dry soil and will reradiate heat during the night."
And you can always cover them. Bed sheets are better than plastic, which can damage plants when the sun comes out.
I am getting a little lazier as time goes on. Orchids that are close to the house on my screen porch only get covered with a sheet on nights when temperatures drop under 40. I no longer run around flinging beach towels over the orchids tied to trees. My hope is that they are now well-established and will glean some warmth from the tree trunks and their overhead canopies.
I have a few special orchids — one (LC Gold Digger) that has produced as many as 75 small cattleyas in a season and another unnamed cattleya that often produces 15 or 20 large blooms. They normally sit under trees and are usually full of buds at this time of year. They get moved into the garage.
Maybe my other orchids will take note that the good performers get the best treatment.
Christine Winter Juneau is a National Wildlife Federation Habitat Steward. You can reach her at firstname.lastname@example.org.