“Wait to cut down root-hardy perennials such as lantana, esperanza, and poinciana. Often a freeze will defoliate the plant but not kill the stems giving you a stronger plant in the spring.” ~Dr. Calvin Finch, Director of Water Conservation
“Plants can get used to freezing weather if they are exposed to it consistently and gradually,” according to Monte Nesbitt co-author of Protecting Landscapes and Horticultural Crops from Frosts and Freezes. “But in Texas, intermittent warm periods can make it hard for plants to adjust and therefore be more vulnerable to frost or freeze damage.”
A sudden, steep plunge in temperatures which we can get as early as November can bring about a freeze that includes winds, cold air masses, clouds and precipitation over a period of days as it moves across the state. “For plants, that means damage from the low temperatures as well as from the wind from the stalk to the top,” says coauthor Robert “Skip” Richter said. “When the water inside plant cells freezes, ice crystals form that can pierce and damage the cell walls, killing the cells. As temperatures rise, fluids leak out of those cells, and they begin to decay.”
A frost, by contrast, happens when the sky is clear and there isn’t much wind. The amount of radiation given to the plant by the sun is lost gradually during the night to the freezing point just before sunrise. Frosts can be severely damaging as well, but normally only at the top or most exposed part of the plant.
Plants that are permanently set in the landscape can receive some protection from semi-permanent structures such as polyethylene film-covered structures (hoop houses, for example), windbreaks, and mounds of soil or mulch heaped around the lower trunk.
By Kathleen Philips, Media Relations Manager, Texas A&M AgriLife