After an abnormally-warm fall and early winter, southern Florida finally experienced some significant cold fronts in January. For most locations in the region, the coldest readings were recorded on Sunday, January 18, when widely-scattered frost was reported. While chilly weather can prompt flowering in some fruit species, we remain pessimistic that lychees will produce significant quantities this year. And we have yet to observe the kind of flowering in mangos that we hoped the low temperatures would trigger.
But, as we know, cold weather more often has a dark side. While vegetable and fruit crops were spared significant damage this month, that does not mean that tropical ornamental plants uniformly fared so well. Even where temperatures fell no lower than the upper 30s, a number of species suffered damage that merits monitoring and perhaps some treatment. Here are a few suggestions:
Don’t be in a hurry to remove leaves affected by the cold temperatures and high winds. They will provide an extra measure of protection if there is another outbreak of winter weather. Remove the brown leaves when temperatures become reliably warmer and new growth can be observed.
Don’t assume that your plant came through unscathed just because it exhibits no outward signs of damage. Palms in particular may look fine even though they have suffered internal damage to the bud that may lead to the plant’s death months later. To be on the safe side if you own a species known to be cold-sensitive, pour or spray a fungicide (diluted according to label instructions) directly into the bud at the spot where new leaves emerge, and administer a second dose 7-10 days later. Alternatively, you may apply 3% Hydrogen peroxide, a bacteriacide, into the bud. But avoid the temptation to treat your palm with both types of chemicals; they are not compatible.
Maintain standard watering habits. Ample rainfall the last week of the January relieved homeowners of the need for supplemental water, but you should stay alert for the sudden onset of dry weather that requires intervention on your part.