For me, it feels like a mortal gardening sin to not try to overwinter something from the garden each winter. I come from a long line of gardeners that had this, that or the other cutting or whole plant limping along in the basement or living room window all winter long.
As tropical plants have grown in popularity for use in outdoor landscaping, my guilt about trying to overwinter plants has intensified—because let’s face it, tropical plants can be expensive.
Most will not survive the cold temperatures of an Illinois winter without being moved indoors. It’s not an impossible task, but will require some planning and preparation. Unfortunately sometimes you can’t save them all—despite what you might have read, or what your grandmother taught you. It doesn’t make you a bad gardener. It may just make you a smarter one.
Overwintering tropicals like cannas, elephant ears, caladiums and dahlias is best done by allowing the tops to turn brown after the first frost, and then dig the underground tubers or rhizomes. There are many different ways to store the tubers and rhizomes.
In order to successfully survive the winter, tubers and rhizomes need to be in a cool 40 to 50 °F area, with good air circulation. An unheated garage or shed is a good choice. Some sources recommend removing all of the soil, and packing the tubers and rhizomes in ventilated milk or bread crates loosely with sawdust, peat moss or vermiculite which will keep them from shriveling.
This sounds like an awful amount of work requiring time I just don’t have. I used to just avoid planting anything that needed to be dug up in the fall, but one year my husband talked me into planting “just a few” elephant ears and cannas. And I may have bought “just a few” dahlias as well that year.
The dahlias that I planted in the ground never did get dug up that fall, though I had great intentions to do so. We dug the cannas and elephant ears, but just left them in a bin in the garage. They survived.
Over the years our method evolved to routinely use standard plastic storage totes for cannas and elephant ears. We knock most of the soil off after digging them, spread them out to dry for a few days, then store in standard plastic storage bins with the lid cracked open in our crawl space.
When I tried growing dahlias again, I planted some in a pot rather than in the ground. Instead of worrying about finding the time to dig them up in the fall and store them, I just brought the whole pot into the garage, removed the frost-killed top, put it on a shelf and forgot about it for the winter.
The Horticulture Educator in me kept saying it wouldn’t work, that I would end up with rotten diseased bulbs since I left the dahlia in soil. But it worked. It worked quite well in fact.
Now if I had had disease problems the previous year, it would have been likely I would have just overwintered the disease as well—but my plants had been healthy, and produced healthy plants the next year.
They actually started growing in the garage the following spring before I had even watered them. I gave them a dose of fertilizer and set the pot outside and had great blooms again that year.
I’ve overwintered the same pot of dahlias for at least 5 years now. I’ve noticed the number and size of blooms has trailed off the last couple of years though the plant is vigorous. I suspect the tuberous roots have crowded the pot to the point that they need a bigger pot or need to be divided. I will probably wait to investigate until next spring. I don’t want to interfere with my successful overwintering method!
But what about plants that don’t have a tuber or rhizome to dig? It’s natural to want to save your tropical plants, as many of them are expensive to purchase each year. But remember overwintering plants indoors requires space and time to care for them. Even if plants are brought indoors and allowed to go dormant, they still need to be checked on from time to time.
Many tropicals, including banana, hibiscus, mandevilla, bougainvillea, and angel’s trumpet will go dormant if brought indoors and the soil is allowed to dry out. The leaves will turn yellow and drop (in the case of banana trees, all foliage should be cut down to the soil level), and the plant should then be moved to a location that is 40 to 45 degrees. Throughout the winter, keep the soil barely moist, watering sparingly when the soil is dry two to three inches deep in the pot.
If you have good light and space, you may want to attempt to keep your tropicals actively growing through the winter. I have kept tropical hibiscus growing and flowering through the winter using supplemental lighting. The plants produce a good flush of flowers in the fall and again in the early spring.
But they do tend to get leggy and spindly even though they are under lights. When moving tropicals back outdoors in the spring, hibiscus in particular will benefit from a good pruning and a dose of fertilizer to encourage more bushy growth.
Four years ago when I was pregnant with my son, I let my tropical hibiscus overwinter in a dormant state in our attached garage purely out of necessity. I physically couldn’t lift their large pots up the few steps into my house with my pregnant belly in the way!
This also saved me the yearly “discussion” with my husband about whether we really needed so many plants in the house. The hibiscus lost their leaves and sat in their naked state all winter and leafed out the following spring without missing a beat.
The following winter of 2013-2014 was a different story. I will admit I didn’t remember to water them as often as I should have, but the temperature in my garage was a lot colder than it had been in previous winters. During the coldest periods that winter, the temperature in my garage dropped into the 30’s.
With all the new baby gear multiplying in our house that year, I just didn’t have the room indoors for the hibiscus anymore, so I lost them that winter.
Another major factor to consider in overwintering tropicals is involuntarily overwintering pests as well. Bringing in containers of tropicals typically also brings along hitchhikers that are probably not be welcome in your home.
Some pests don’t show themselves until a few days or weeks after being brought indoors. A minor example of this is pots that have been moist all summer outside usually harbor a number of pill bugs (you may know them as the roly poly). After moving a piece of furniture over the winter it’s not uncommon to find a graveyard of them in the corner of the room. As the tropical plants in pots dry out indoors, the pill bugs move out looking for moisture and die along the way.
Some pests are a lot bigger (and scarier depending on your personal opinion). During my tenure with Extension I fielded several calls from homeowners that brought plants in to overwinter indoors and brought mice along with them. In every case it was a larger pot that had been brought indoors.
Soon after that the homeowners noticed soil being tracked around the house and upon inspection they found a burrow in the pot. A mouse trap remedied the situation in all cases, but you may wish to bring plants into the garage or somewhere similarly not “quite” inside to inspect them before they come completely indoors.
If you are trying to keep your tropicals actively growing, and conditions aren’t perfect (they rarely are indoors, even in a greenhouse) you will likely have problems with common houseplant pests such as mealybugs, scale, and spider mites.
All of these pests can be controlled indoors, but the question is whether you really have time to dedicate to controlling them. Left unchecked, these pests will spread to other plants and create quite an infestation.
If you have houseplants with a lot of sentimental value, you may want to be selective about tropicals you bring indoors. You need to honestly assess whether it’s worth the risk to bring every tropical indoors, none of them, or a select few.
Another option to consider is taking cuttings of your favorite plants to start indoors so you have a small plant to start with next spring. This may be a way to overwinter more of your favorites in less space.
Overwintering tropicals can be a way to extend your gardening pleasure into the winter months. Many people look at it as a challenge and get great satisfaction when they are successful in producing plants from year to year.
Initially it really pained me to admit I didn’t have the time or space to overwinter all the plants I was accustomed to offering winter accommodations. I could imagine my relatives chiding me for “wasting” money on tropical plants that I didn’t at least try to save.
But as a result of paring down our winter time plant guests, I’ve come to realize I actually enjoy taking care of less plants more than a whole menagerie. It’s a lot less work, less pest problems, and a lot less stress overall. For me at least, that’s a way to garden smarter.
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Very informative! Thanks.
Thanks I’m glad it was helpful!