The first step to protect tropical plants and palm trees from cold weather involves watering. Gardeners should water all landscape plants at least 24 hours before the predicted freeze. And with more record cold on the way the time to act is now.
Covering Plants During a Freeze, Mini-Greenhouses and Cold Frames
For small or young plants, gardeners can create a mini-greenhouse to protect the plant from the cold. Cut the top 1/3 off a soda bottle to create a plastic dome; place the plant inside the dome and sink the edges into the soil. This tiny greenhouse will retain heat, protecting the plant from freezing temperatures.
For larger plants, gardeners can create a cold frame. More permanent cold frames can be constructed out of wood and plexiglass. Other cold frames are made out of PVC pipe and plastic sheeting. Cold frames protect the plants from the cold weather; they operate on the theory of "if you can't bring the plant to a greenhouse, bring the greenhouse to the plant."
Even a cardboard box can be turned into a homemade cold frame. The top panel of the box must be cut away to create a window; use plastic sheeting or a few layers of plastic wrap (taped in place) to create the window. Put the box over the plant; it will serve as a makeshift cold frame, protecting the plants from the cold wind and freezing temperatures for a short period of time – this homemade cold frame is perfect for Florida, where it rarely rains during the winter (the cardboard will disintegrate once wet.)
On the day of the freeze, gardeners must cover plants to protect them from the cold (unless they're protected by a mini-greenhouse or cold frame. Special insulating fabric and frost blankets for plants can be purchased from most nurseries and home improvement stores, but in a pinch sheets and blankets can be used to cover the plants, protecting them from frost and freezing temperatures.