Central Florida has a climate that allows us to grow many tropical and subtropical plants, and our usually mild winters allow us to grow vegetables and flowers during the cooler months.
Freezes and frosts are not unknown here, though. In fact, although they don’t occur regularly, freezes can be quite severe in central Florida. Since it is not possible to know more than a few days beforehand if a freeze is going to occur, it is wise to take a few precautions and to know what to do when the temperature goes below freezing.
Start prep in the Fall
One thing that can be done in November is to help “harden off” lawns and woody shrubs and trees by applying a fertilizer high in potassium, such as Sunniland Bloom Special. Keep in mind that this sort of treatment helps only with woody plants such as hibiscus and ixora, and will not help palms, heliconias, bananas, and other non-woody plants.
When You Know a Freeze is On the Way
There are a number of things that can be done to protect plants once a freeze is imminent which involve covering or coating the plant in some way. Frost cloth is a product designed specifically to protect tender crops from frost. It can be used the day before the freeze, but don’t wait until the last minute to buy it, since it might not be available. Keep in mind that the coldest days are often also the windiest days, so frost cloth or any other covering must be securely fastened or weighted down.
Other products, such as weed mat, blankets, or plastic, can also be used to cover plants, but plastic alone or weed mat alone do not offer much protection. Blankets that are then covered with plastic can supply protection if used properly.
Always turn off all irrigation before a freeze.
In the event of a very severe freeze, the graft unions of valuable fruit trees or even the bases of shrubs and other plants can be protected by banking them with soil or mulch. To do this, simply pile soil or mulch around the trunk of the plant to a point well above the graft union. The entire top of the tree might die, but at least it will be able to recover.
After a Freeze
Freeze-damaged trees usually do recover the following summer. Icing of plants with irrigation water is a technique best left to professionals, since it can cause damage far worse than the freeze alone would cause. If freeze damage occurs, you’ll want to wait to cut back damaged plants until they begin to regrow in the spring and the danger of frost is over.
One exception to this rule is Frangipani (plumeria); if a Frangipani is damaged by freeze, it should be cut back as soon as you can determine the extent of the damage.
Freeze-damaged palms should be treated promptly with a drench containing copper fungicide. Pour the solution in the bud of the palm where the new leaves emerge.
One last caution: Always protect potted plants from freezing temperatures. In containers, even normally cold-hardy plants can be killed by a freeze, since the roots are more exposed than they would be in the ground. Either move the pot to a warmer location, or cover the pot with insulation or blankets.