Cold Protection For Commercial Agriculture and Home Owners
According to the University of Florida’s automated weather network (FAWN), temperatures are expected to drop to frost/freezing levels tonight. This dilemma poses great concern for growers of winter vegetables, citrus, strawberries, ornamental plants, ferns, and many other crops. This article suggests several methods of cold protection that can be used to protect crops.
In a few isolated situations heaters can be used to protect high cash crops. This method is deemed expensive. For citrus, if the night is calm, wind machines can be very effective in mixing mix warm air aloft with cold air that has settled next to the ground. "Heat blankets" provide a much more efficient alternative to capture heat which has been stored in the ground during the day and is radiadated back to the sky at night. This method of cold protection works well with other low growing crops, but must be removed in a relatively short period to avoid damaging the plants.
By far the most widely used method of cold protection is the application of water. Some crops such as ferns and strawberries utilize relatively large amounts of water to protect the entire crop, while citrus uses much smaller application rates per acre to protect the tree trunk and scaffold limbs. When using water, please determine what are the critical temperatures for the crop(s) and then turn systems on and off to keep from reaching damaging levels while at the same time minimizing water use.
FAWN has two management tools to assist growers that utilize cold protection methods. The first is the "Brunt Minimum Temperature" guide that can be helpful in determining if critical temperatures could be reached on a given night. Read the background material to understand the limitations and rational behind this tool. The second aid is for growers using water for cold protection. "The Wet Bulb Irrigation Cutoff Tool" is highly recommended for every grower using water for cold protection. This tool provides a safe cut off temperature based on the moisture content of the air. This tool is reported to save growers millions of dollars and reduce water demand by billions of gallons. Read more about this simple, but critical management tool at the FAWN website
http://www.fawn.ifas.ufl.edu. FAWN provides valuable links - EDIS TOPIC "COLD"; EDIS search results for "Cold Protection". These links can further help growers understand frost/freeze probabilities and how to deal with cold weather.
Cold Protection For Home OwnersPlease remove all tropical plants to warmer environments or locations with temperatures exceeding 40
0 F. For larger container or in ground tropicals, these should be covered. Flannel blankets, cotton sheets or commercial type wraps are ideal thermo insulators. In wrapping plants, please allow the foliage ample space for flexibility and air circulation. Avoid using plastics; these materials are poor insulators and transfer cold directly to the plants. Remember the purpose of coverings was to generate heat and will create burns when the temperature rises. As such, all coverings should be removed shortly afterwards.
For additional information please contact Martin County Extension at (772) 288 5654.