Preparing Landscape Plants for Winter

Cold damage, from low temperatures, frost or a hard freeze, is a hazard to many outdoor plants in Florida. Even in south Florida where temperatures seldom reach the freezing mark, cold injury can and often does occur. With proper cultural practices and several protective steps, damage from low temperatures can be cut to a minimum.

Many plants go through a "hardening process" with the advent of low temperature. This process induces a natural protective device in plants, enabling them to survive low temperatures. Light is important in this hardening process. Plants receiving little or no light often do not develop hardiness, even though the temperature is acting to encourage this natural occurrence.

Many of Florida's sub-tropical plants do not go through this hardening process so we must try to reduce cold damage on these plants by artificial means. Nutrition is very important for increasing a plant's resistance to cold injury. A plant that is favorably supplied with all elements essential for growth will survive lower temperatures and recover faster from cold injury than plants not receiving proper fertilization. In other words, a plant suffering from a lack or inbalance of fertilizer will be more susceptible to cold injury. An optimum level of fertilization should be maintained throughout the year. Most plants grow during the winter but at a slow rate. The rate of fertilization should be reduced proportionately, say to one-third the normal rate, but should not be completely stopped. This is also true for watering. Plants require water during the winter just like the rest of the year. Remember, people don't stop eating and drinking in the winter and neither do plants!

Another way to minimize cold injury is by suitable windbreaks. Windbreaks reduce wind speed and also conserve heat in an area. Evergreen plants make excellent windbreaks which can be effectively placed so that an area stays warmer than it would if it were in the open. You can thus protect some of your tender plants by placing them inside a windbreak of evergreens.

Covering materials such as cloth, polyethylene plastic and paper can also be used to reduce cold injury. These temporary coverings trap heat and maintain higher temperatures near the plant. Other materials such as leaves or soil can be piled around the base of plants to keep the stems from freezing. Leaves may be injured or even killed but these coverings may prevent the entire stem and roots from being killed.

Sprinkler systems have also been used for cold protection. A constant flow of water over the plant may be of value, however, if the supply of water is stopped or is not supplied fast enough, ice can build up to the point where its weight breaks the branches of the plant. This method is usually not suitable for homeowners, since large quantities of water are needed and most irrigation systems are inadequate.

To summarize, a good healthy plant is the best insurance against cold damage. A healthy plant means a proper fertilization and watering program are used. Use windbreaks or protective coverings for the entire plant or at least for the main stem when a cold snap is anticipated. If all fails and the plant freezes, replace it with a more cold tolerant species or grow that favorite ornamental as a pot plant which can be moved indoors those few cold days we have in Florida.