Overwintering Tender Tropical Plants: Three Proven Methods

With blooms like this, it’s easy to make time and space for saving a brugmansia.

Bougainvillea, jasmine, mandevilla, banana, agapanthus, taro—today’s garden centers offer a thrilling palette of tropicals for gardens, decks, and patios. But when fall arrives, what happens to these cold-sensitive beauties? The easiest route is to let frost kill them and compost the remains. Most gardeners, though, are too tender-hearted—and thrifty—to waste a good plant. If you grew tropicals this summer and want to keep them alive until spring, you have three options:

1. Keep the plant in active growth in a warm, sunny spot (sunroom or heated greenhouse).
2. Take cuttings and let the “mother” plant die; root cuttings for new spring plants.
3. Allow the plant to go dormant and store it in a cool, dark place until spring.

Overwintering Techniques at a Glance

• Overwinter as houseplants: cordyline, phormium, palms, croton, bamboo, jasmine, allamanda, bougainvillea, hibiscus, citrus
• Keep dormant in cool, dark place: brugmansia, banana, dwarf canna
• Store dormant bulbs/corms/tubers: begonia, dahlia, ginger, sweet potato vine, colocasia, caladium, canna, calla

1. Keeping Plants in Active Growth

If you have a sunny window at 60–70°F, most tropicals will grow and even bloom through winter. Bougainvillea, jasmine, citrus, hibiscus, and geraniums thrive with plenty of light and nighttime temps above 40°F. Small plants do well under grow lights on a 12-hour timer. Bring plants indoors before cold weather and definitely before frost. Expect some leaf drop as they adjust. Water as needed but keep soil on the dry side. Avoid crowding—good air circulation deters pests and diseases (run a small oscillating fan a few hours daily). Maintain humidity at 30–45% by misting or placing a water tray nearby; in cold climates, keep it below 30% to prevent window condensation.

Ideal winter temps: ~50°F night, 65°F day. Warmer air causes leggy growth and bug issues. Watch for whiteflies, spider mites, scale—check weekly. Control early with insecticidal soap. For serious infestations, dunk foliage in a dishpan with water and a teaspoon of liquid dish soap, or shower large plants. Let dry, then spray with insecticidal soap.

Plants in active winter growth benefit from pruning once or twice to rebalance foliage-to-root ratio and yield cuttings. Coleus, plectranthus, and geraniums respond well. In spring, repot and start fertilizing; Plant Health Care organic water-soluble fertilizer works well.

2. Taking Cuttings

Herbaceous, soft-stemmed tropicals like plectranthus, coleus, and geraniums can be tricky to overwinter whole. Instead, take fall cuttings and let the mother plant die. Root succulent young stems (not woody ones) in water on a windowsill—only the stem, no leaves, in water. Once roots form, pot each cutting in a 3–4 inch container on a windowsill or under lights. Fertilize regularly. You’ll have a batch of new plants for spring and be a hit at plant swaps!

3. Managing Winter Dormancy

Cannas are especially easy: dig up tubers and store in pots with soil.

Some tropicals need or prefer a winter rest. Care depends on available space and plant type (soft-stemmed, woody, or bulb-like). Bulb/tuber plants (elephant ears, caladium, sweet potato vine, canna lily) should get nipped by frost before coming indoors—it signals season’s end. Then either leave them in pots, keeping soil barely moist, in a cool, dark place; or trim stems, dig up bulbs, label, wrap individually in slightly moist newspaper or peat moss, place in a black plastic bag, and store cool and dark. Either way, maintain 40–50°F. Check monthly—bulbs should stay firm; mist storage medium if drying. In spring, repot, fertilize, and place in a sunny window.

Woody tropicals (jasmine, brugmansia, tibouchina, bananas) come indoors before first frost. Let them rest in a cool (40–50°F), dark place—leaves will yellow and drop. Store in an unheated basement, root cellar, garage, or cool closet. Keep it dark (loosely enclose pot in a heavy black trash bag) and above freezing. Don’t cut back until early spring unless space forces it. Water sparingly monthly, keeping soil barely moist. In early spring, revive by repotting in fresh soil, watering thoroughly, and giving a weak liquid fertilizer. Provide bright filtered light, gradually acclimating to full sun. Give about a month of indoor/greenhouse growth before moving outside.

When reintroducing tropicals to outdoors, do it slowly—shield from direct sun and wind for at least a week or two. Slow acclimation slides them into active growth; early stress can stunt or kill.

Overwintering involves trial and error; a technique that works for one plant or winter may fail for another. Be prepared to lose a few. See the Overwintering Techniques box above for general guidelines. For specifics on 100+ tropicals, consult Hot Plants for Cool Climates by Susan A. Roth and Dennis Schrader (Houghton Mifflin, 2000).