Autumn is a time of soul-searching for gardeners who love the tropical look—as in, “Why the heck don’t I live in a frost-free climate?!?” Or, looked at from a budgetary standpoint, “Why did I spend so much on plants that are going to freeze to death any minute now?” Take heart, fellow gardener, many of your favorite tropicals now preparing to meet their fate can be rescued. You’ve just got to know a few tricks.
For overwintering purposes, I divide tropicals into three categories: soft-stemmed plants with fibrous roots as skinny as a supermodel; plants with big fat rockin’ tuberous roots; and those that produce woody stems or a storage crown along with fibrous roots. Scientists may frown at my classification system, but it works for figuring out how to overwinter your plants!
Soft-stemmed plants include colorful coleus, pentas and plectranthus. These overwinter best from rooted cuttings that wind up on your warmest, sunniest windowsill. Water sparingly—winter losses often come from root diseases triggered by soggy soils. Inspect often for pests like aphids, whiteflies and spidermites; it’s much easier to quell a small infestation than an army.
Big-bootied tropicals like cannas, bananas, gingers and elephant ears overwinter from succulent tuberous roots. They make fab houseplants if you just happen to have a furniture-free sunroom you weren’t using, but they also can be sent into dormancy to spend the winter in a cool, frost-free location—like a garage, chilly basement or even the crawl space under your house. (Ixnay on the crawl space, though, if it’s crawling with mice.) If your plants are growing in containers, you can simply remove the foliage and shove the pots into your designated storage space. If they’re in the garden, dig them just before frost (or at least before hard freezes damage the crowns), jettison the leaves and overwinter the tubers in uncovered tubs filled with barely damp sand, bark or loose potting mix. Some gardeners apply a fungicide or coat the tubers with an antidessicant spray to keep them from drying out. Inspect your tubers every few weeks, and discard or treat them at the first sign of rot.
Many tender tropical plants are actually perennial woody shrubs with fibrous root systems. We temperate-zone gardeners consider them annuals because they’re too wimpy to tough it through our frosty winters. Lantanas, cupheas, angel’s trumpets (Brugmansia) and some salvias are woody plants that can be forced into dormancy—cut them back to remove the foliage, then store them in a cellar or garage where it’s cool and dark. Keep their root balls barely moist and watch for signs of sprouting next spring. Tropical grasses like burgundy fountain grass (Pennisetum setaceum ‘Rubrum’), chocolate sugarcane (Saccharum ‘Pele’s Smoke’), and lemongrass (Cymbopogon citratus) have fibrous roots but sturdy storage crowns. Give them the same treatment as woody tropicals.
While overwintering tropical plants indoors isn’t foolproof, there’s an excellent chance that your treasures will live to see the sun shine next spring.