Overwintering tropicals

1011 N. Woodlawn

Kirkwood, Missouri

63122

314-965-3070

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You have five basic choices when it comes to carrying tropical plants through the winter:

· Over-wintering them indoors as a houseplant

· Storing them as dormant plants, tubers, or bulbs

· Collecting seed to start again in the spring

· Leaving them outside, but protected

· Taking cuttings to root over the winter

Over-wintering indoors
Many tropicals perform well as houseplants, but only if they get enough light and humidity.  Use grow lights if you don’t have a sunny window, and run a humidifier.  Don’t let the temperature fall below 60 degrees.  Expect some leaf drop when they are first brought indoors.

Move your plants back outdoors in the spring very gradually.  Too much sun too soon will burn the new growth and may kill the plant completely.  It’s like going to the beach on the first day of summer without sunscreen.

Hibiscus, bougainvillea, mandevilla, banana, palm, citrus, fig, duranta, brugmansia, cordyline, phormium, abutilon, ginger, lantana, jasmine, and gardenia fall into this category. 

Storing them as dormant plants, tubers or bulbs
Elephant ears, caladiums, canna, calla lilies, sweet potato vines, gladiolas, and dahlias are from bulbs, tubers, or corms.  Cold weather will cause a bulbous tropical to go into dormancy.  Allow the plant to go through the first frost, then cut back the top and dig it up.  Wash off all the soil and let them air dry for a day or two.  Examine the bulb for rot or damage and cut away any diseased portion.  Wrap each bulb loosely in newspaper, then label and store them in a black garbage bag.  Keep them in a cool (but not freezing) dry dark place at around 40-50 degrees.  A basement, garage, winterized porch, or even the back of a closet make a good resting place. Dormant bulbs can be revived by potting them up, watering, and moving them to a sunny space.  You can do this prior to spring to give plants a head start before moving them outside.

Bring woody tropicals inside for storage just before frost.  Don’t cut back or prune woody plants in the fall.  Dig them up, plant them in containers with potting soil (a soil-less mix), and store plants in a cool place at about 40 degrees.  All the leaves will yellow and drop off.  New leaves will grow when you return the plant to warmth and light.  Prune the plant to shape at this time.  Keep dormant plants on the dry side.  Check soil moisture once a month and water lightly if they appear dry.  Gradually introduce plants back into the light, and they will be ready for the garden.

Hibiscus, bougainvillea, mandevilla, banana, palm, citrus, fig, duranta, brugmansia, cordyline, phormium, abutilon, jasmine, ginger, and lantana fall into this category.

Gardenias — a special challenge
Gardenias are one of the most difficult plants to grow and bloom indoors successfully because they have strict temperature requirements.  Temperatures between 55 and 65 degrees are essential when gardenias are in bud or bloom.  Bud drop occurs above 70 degrees, and bud deformity occurs below 55 degrees.  Letting the soil get too dry or a change in environment will also cause bud drop.  Do not re-pot or fertilize at this time.

When the flowers are finished, you can move your gardenia to a sunnier spot and not worry about warm temperatures.  Direct sunlight, high humidity, and acidic soil (5.0 pH) are also important.  Avoid repotting until it is utterly rootbound.  Use an acid fertilizer, such as Miracid, but don’t overdo it.

Gardenias can bloom at almost any time of the year.  Flower buds form according to the following regimen: Prune back old growth (usually in the spring); promote new growth with lots of light and warm temperatures during the day (summer); allow temps to drop to 60 degrees at night (fall or early winter).  It is up to you to decide when you want to introduce this regimen.  Obviously, it is harder to achieve the lower nighttime temperatures during the summer.

Storing begonias
In fall, once flowering ceases and before the first frost, bring in begonias for the winter.  Leave the stems until they dry and pull off easily.  Store “as is” in pots or dig up the tubers.  Dug tubers should be allowed to dry for a few days and then stored in layers of slightly moist vermiculite or sawdust.  Keep in a room that stays about 40-55 degrees.

Overwintering geraniums
Dig your geraniums before a hard freeze and shake the soil from the roots.  Set the plants in a shady spot and let them dry for a few days.  Most of the leaves will dry up and fall off.  Remove most of the dry leaves to prevent mold from growing over the winter.

Store the stems in a box, with the roots up and the stems down.  This forces moisture downward into the stems.  Close the top of the box.  Store in a cool, dry place at about 50 to 60 degrees.  You may want to check for mold every few weeks.  Discard any shriveled, dried out stems. 

In spring, pot them up.  Tuck the plant into potting mix deep enough so that two leaf nodes are below the soil line — that’s where new roots emerge.  You should see new growth in 1-2 weeks.  The trick is to water cautiously — only when the soil dries out to about an inch down.  In 4-6 weeks, plants are ready to be moved to the ground, if desired.