Cold Protection of Landscape Plants

We have cold weather in our forecast in Northwest Florida and home gardeners are asking about how to protect their tender ornamentals and citrus plants.

Frost cloth covering landscape plant draped to ground with bricks holding it in place along the ground by Johnathan Burns — Frost cloth cover all the way to ground with bricks holding it in place. Photo by Jonathan Burns.

Watering landscape plants before a freeze can help protect plants. A well-watered soil will absorb more solar radiation than dry soil and will reradiate heat during the night. This practice elevates minimum night temperatures in the canopy of citrus trees by as much as 2°F. But the root area needs to be watered well before the freeze strikes for this to work. This is particularly true when we have the less common dry cold front.

Radiant heat from the soil protects low growing plants on calm cold nights, while tall, open plants receive little benefit. Radiant heat loss is reduced by mulches placed around plants to protect the roots. For cold sensitive perennials, the root system is all that needs to be protected since the plants die back to the ground annually.

Plants in containers can be moved into protective structures. Containers that must be left outdoors should be protected by mulches and pushed

together before a freeze to reduce heat loss from container sidewalls.

Coverings protect more from frost than from extreme cold. Covers that extend to the ground and are not in contact with plant foliage can lessen cold injury by reducing radiant heat loss from the plant and the ground. Foliage in contact with the cover is often injured because of heat transfer from the foliage to the colder cover. Some examples of coverings are cloth sheets, quilts or black plastic. A word of caution with plastic: It is necessary to remove plastic covers during a sunny day or provide ventilation of trapped solar radiation. I avoid the use of plastic coverings for this reason. The excessive heat buildup under plastic during a sunny day can do much damage to the plant. A light bulb under a cover is a simple method of providing heat to ornamental plants in the landscape.

Here is a UF/IFAS Extension link with more information on preparing and protecting the landscape from cold weather.

gardeningsolutions.ifas.ufl.edu/care/weather/preparing-the-landscape-for-cold-weather