by Laurel Schiller Dan Walton
Many folks who come to this part of Florida from northerly climes assume that we live in a tropical climate where cold and frost need not be taken into consideration when planting. Although we do have relatively warm winters with an average low temperature in January around 50o, we also average at least one morning when the temperature is at or slightly below freezing for a few hours. In some winters there are no such days, while in other winters there may be three or four such days. Occasionally there will be a temperature sufficiently low to damage or kill most plants that are not cold hardy.
Crucial to this analysis is the location of your house, because during cold spells there is usually a temperature gradient from the Keys eastward. At our nursery 12 miles east of I-75, we may be 6 or 7 degrees lower than is experienced by someone on Siesta Key. This is why we keep all of our temperature sensitive plants in greenhouses during the winter. Although slightly below freezing for a few hours doesn't sound terribly stressful, many tropical plants will suffer damage ranging from loss of leaves, die-back of twigs, to death. Most plants that you see flowering in December or January fit this category.
In landscaping your house you should be aware of the cold hardiness of plants, particularly those that are perennial and that you hope to have for a number of years. Of course, you may be willing to gamble on a cold-sensitive plant because you particularly like its appearance. If you do, try to plant it close to the south east corner of your house. Also be prepared to cover it when temperatures are scheduled to drop.
You can save yourself this trouble, however, by installing plants that are quite cold hardy. This is especially important when considering trees for your property. Trees are a long-term investment. It takes time to get them established and money to provide the maintenance necessary to create a healthy canopy. Cold damage to trees can be devastating. Tropical trees that are cold sensitive can suffer branch rot after a severe frost that can eventually involve the trunk and cause damage all the way down into the base of tree. This will compromise its structure and may require that you pay to have the tree cut down and hauled away. This can be very expensive particularly if it is a sizable tree near your home or in a part of the yard where it will be hard to get to.
There are a number of native trees that are cold hardy. Many of them naturally range into North Florida where they are often subjected to temperatures in the high teens or low 20's. The trees include red maple, laurel oak, Florida and winged elm, bald cypress and sycamore. These trees are deciduous and lose their leaves for a time. In this climate, however, they are bare for only a few months. Southern magnolia, slash and long-leaf pine, red bay, red cedar, dahoon and East Palatka hollies, live oak, sweet bay magnolia, and loblolly bay are evergreen and do not go through a bare period.
Shrubs that are cold hardy include wax myrtle, Simpson stopper, Florida privet, Walter's viburnum and Yaupon holly. These shrubs can be used as screening because they don't suffer in cold weather and will not drop their leaves. Dwarf yaupon holly, as well as dwarf variants of Walter's viburnum, Indian hawthorne, and coontie are low-growing shrubs that are also cold-hardy and can be maintained easily under four feet tall. These should be used more often at the entrances to homes instead of many colorful winter annuals and cold-sensitive tropicals that will require replanting after a frost or perhaps severe pruning come spring. Use them sparingly and incorporate more cold-hardy plants into your homescape.