Over-Wintering Tropicals

Most tropical plants are perennials in their native habitats, thriving in mild, year-round temperatures.  But in this area, tropicals are not winter hardy.  None will be able to withstand the frigid winter temperatures.  Most people who grow tropicals love the challenge of keeping them alive until the next growing season.  After awhile these plants become like old friends that you look forward to seeing in your garden year after year.

Over-wintering tropicals generally get better and better each year because they achieve such impressive size.  Being able to start your growing season with fully grown specimen plants makes an immediate impact in your garden.  That in itself is reward enough for all the effort it took to over-winter

Many tropicals are costly.  The rarer the species, the harder they are to find, the more they cost.  Once you have found a rare treasure, you will surely want to learn how to carry it through many winters.

Many tropicals that you have been growing outdoors in summer will look wonderful in the fall.  When the annuals and perennials have diminished the tropicals will still be going strong.  If this plant will flourish as a houseplant, all the more reason to bring it in and enjoy it longer.

The way you over-winter a tropical plant largely depends on the particular plant.  The general idea is to mimic the way the plant rests during its natural dormancy period, if it has one, without allowing it to freeze.  In a tropical climate where daylight length and temperatures vary only slightly throughout the year it is the seasonal dry periods that induce dormancy.  The plants may actually drop their leaves for a month or longer to enter a period of slowed growth.  But changes in climate will also slow the plant down without killing it.

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

Many tropicals perform well as houseplants but only if they get enough light and humidity.  Use grow-lights if your available light is not sufficient and run a humidifier to help boost the humidity.  Also cooler air seems to be less dry.  Tropicals do much better in the winter with day and night temperatures in the sixty degree range.

When moving a over-wintered tropical as a houseplant back outside I the spring, do this 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 and laying out in the sun all day without sunscreen.

Start by taking your plant outside on a cloudy day and place it beneath a shade tree.  Leave it there for a few days and then move to a slightly brighter location.  Give it time in the sun for an hour or two each day but not at midday.  Finally after a few weeks you may move it to its permanent sunny location, but make the move on a cloudy day.

Elephant ears, Caladiums, Canna Lily, Sweet Potato Vine, and Dahlies are from bulbs, tubers, or corms, (commonly referred to as bulbs.)  Cool and frosty weather will cause a bulbous tropical to go into dormancy.  So will holding back water.   Allow the plant to go through the first frost, then cut back the top, dig it up, label it and store it in a cool, (but not freezing) dry dark place.  A root cellar, basement, garage, winterized porch or even the back of your closet makes a good resting place.  After digging, wash all the soil off and let them air dry for a few hours.  Examine the bulb for rot or damage and cut away any diseased portion.  You can coat them with an anti-desiccant spray to help reduce moisture loss and ward off fungal attack.  Wrap each bulb loosely in newspaper and then store in a black garbage bag.  Ideal temperature to store in is around forty to fifty degrees.  Examine every month to check for signs of rot or decay.  Spray a bit of water on shriveled ones to re-hydrate them.

You can resurrect the dormant bulbs by potting them up, moving them to a sunny space and starting to water them, much sooner than you can plant them outside.  This will give you much larger, fuller plants earlier in the summer.

Bring woody tropical plants inside for storage just before frost.  Don’t cut back or prune woody plants in the fall.  Dig them up from the ground, plant in containers with a soilless mix, not garden soil.  Store plants in a cool, approx. forty degrees, place.  I use an old coal shoot.  All the leaves will yellow and drop off.  New leaves will grow when you return the plant to warmth and light.  Prune the plant into shape at this time.  Keep the dormant plants on the dry side.  Check the soil moisture every two to four weeks and give a small amount of water if they appear dry.  Gradually introduce the plants back into the light and they will soon be ready for the garden.  Just do not introduce to fast.  Soon, your plants will return to their former self and be ready for another season in the garden.

More Resources:
The following link is an eight page color flyer form the University of Illinois Extension.  You will need Adobe Acrobat Reader to view the pages.  If you do not have Adobe Reader installed on your computer you may get it free from www.adobe.com

Tropical Punch!