Institute of Food and Agricultural Sciences
Hendry County Horticulture News
After a Freeze - What Do I Do Now?
Last week's cold spell was just enough to kill or damage sensitive plants throughout the area, and burn turf and ornamentals that were exposed to the frost that settled. Fortunately, the majority of plants were left unscathed, or only slightly damaged. Just a drop of a few more degrees and the situation would be much different. What you do over the next few weeks may make a difference in how well you plants recover from the recent cold weather. In many cases, patience is the best approach. Plants have a tremendous capacity to heal themselves and you may cause further damage by hastily removing plant parts that appear to have been damaged by freezing temperatures.
If flowering annuals or vegetables were killed or burned back, they can be replanted, but be prepared to protect them from future cold snaps. There is a definite risk of more to come, at least through the end of February, and sometimes as late as mid-March. Bananas are very sensitive to cold, and many were damaged. These should be left alone until all threat of cold has passed, and then damaged foliage should be removed. If the damage is excessive, the plant should be cut back to the ground to make room for new plant growth from the base. Even though new growth may initiate from the top of a severely damaged plant, it probably doesn't have the potential to produce a good crop.
Turf will regrow after the temperatures are warm long enough to warm the soil and promote new growth. Meanwhile, water can be reduced to those areas that are cold-damaged - the turf no longer needs it, and it could help promote disease growth. A good fertilization is recommended after the cold is no longer a threat.
Ornamental shrubs should be left alone. It is not a good idea to remove any damaged or dead plant tissue at this time. Even though that part of the plant is dead or damaged, it will still offer some protection from future cold and frost threats. Also, the damage maybe further down on the plant than visible signs show, and it is best to let the plant seal off these areas. After it begins to warm up, dead or damaged plant parts can be removed without opening up stems and branches to disease.
The tropical herbaceous perennials sometimes show the worst damage, and may actually have been killed to the ground. These should be left alone also. There is a good chance that new growth will be initiated from the roots, and the dead plant material left will offer some protection from future colds and frosts.
The cold temperatures, and the duration of these cold temperatures were not low enough or long enough to damage most trees. However, some foliage damage may have occurred, but this will be replaced naturally when the trees begin to grow again. If a tropical tree was damaged, the same procedure used with ornamentals should be applied: leave the damaged or dead material there until all threat of freezing temperatures has passed.
Some of the more tropical palms might have been severely damaged by the temperatures reached last week, particularly those planted in cooler areas. Those that might have some burn are the Christmas Palm, Veitchia merrillii, the Royal Palm, Roystonea spp., native Thatch Palms, Thrinax spp., the Coconut Palm, Cocos nucifera, and perhaps a few others. If these or any other palms are showing signs of damage to the central bud, a chemical treatment to the bud should be done immediately, followed up with a second treatment a few weeks to a month later. A copper-based fungicide is generally used for this treatment.
Extended periods of cool temperatures will also cause nutritional deficiency symptoms in many tropical and subtropical plants. This happens because the soil temperatures drop below the range in which the plant's roots can effectively absorb nutrients. Generally, these plants will outgrow these symptoms once the soil temperatures have risen enough to allow uptake again. However, foliar applications of water soluble fertilizers can aid in the recovery, especially those containing the minor elements.
For more information on protecting your plants from cold weather, check out the UF/IFAS Forida Automated Weather System Links at http://fawn.ifas.ufl.edu/preview/focus_links.html
Since the threat of a frost or freeze exists until early to mid-March, it is best to wait to plant any cold-sensitive plant material until temperatures moderate. Good luck and good gardening.
Gene McAvoy is the horticulture agent with the Hendry County Extension Service. Direct your horticulture questions to PO Box 68, LaBelle, FL 33975, e-mail - GMcAvoy@mail.ifas.ufl.edu or phone 863-674-4092 or 863-983-1598. You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle. Office hours are from 8:00 - 5:00.
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