Our unusually rainy and warm November and December have fattened our tropical plants, but also made them more vulnerable to a sudden drop in temperature, predicted for tonight.
Water plants well as they will be better able to withstand low temperatures than dry plants.
Putting container plants on the south side of the house can help protect them from the wind that accompanies a cold front. Drop hanging baskets to beneath a tree and cover with a sheet. Wind may be more damaging than cold temperatures, pulling moisture from both the plant and the growing medium, so don’t leave them in harm’s way.
Orchid growers know to bring Phalaenopsis orchids inside if the temperature goes below 55. Vandas, too, would like protection when temperatures are in the low 50s to upper 40s. Mature Paphiopedilum orchids like temperatures between 55 and 60 degrees, but not below. Cattleyas also like the 55 to 60 degree nighttime temperature, but temps in the low 40s may stress them. Encyclias can tolerate cold, but evergreen dendrobiums and mule-ear oncidiums cannot. Renanthera and Rhynchostylis orchids want to be protected below 50 degrees. After warmth returns, spray your orchids with a mix of Dithane M45 and Captan (1 tablespoon each to a gallon of water) to avoid disease.
Birds-nest anthuriums are among the cold-tolerant aroids. Generally those plants with leathery leaves will do better in cold (as long as it is not prolonged for days). However, the strap-leaf anthuriums will need protection. Philodendron bipinnatifidum (what we used to call Phil. selloum) is quite cold hardy, but many others may have leaf-burn.
Ixoras will develop brown spots and leaves in even mild cold. Mussaendas, too, dislike cold. Ornamental bananas are more cold tolerant than edible varieties. Tall bananas are going to have leaves ripped by wind, and after days of cold may die back to the ground, but one night of cold should not harm them if they are growing well and disease-free.
Palm lovers know to use a copper fungicide for tender palms; mix according to directions and pour down the growing point if you can reach it. Copper will counter fungus and bacteria.
But do not use on Dendrobium orchids or bromeliads, as it will kill them.
If you have cared for your plants with fertilizer and water at the appropriate times, they should be robust enough to come through with the least amount of damage.