I’ve procrastinated as long as I can. The many non-hardy plants I’ve enjoyed most of this year will succumb to below freezing temperatures tonight unless I act now! There’s nothing like a cold north wind and fast moving front to remind me that I’m out of time to get those tender plants and tropicals off the deck or out of the ground.
Due to the popularity and the striking contribution tropical and other non-hardy plants make to any vista, chances are you too have one or more in your garden, or on your deck or balcony. The good news is you’ll have them for years to come with some good timing and a little care on your part.
The trick is to make sure you protect these cold sensitive plants before they succumb to a killing frost or freezing temperatures. All tropicals can take the heat but most are highly sensitive to cold weather. For the most tender plants, temperatures in the 40’s can do them in. Others can make it through a frost or two but take the sign of this colder weather as their signal for dormancy. In either case, don’t expect them to look very good once Jack Frost has paid a visit.
Some of the most common tropical plants include banana, caladium, elephant ear (Colocasia spp.), angel’s trumpet (Brugmansia spp.), hibiscus and one of the most popular structural plants today, New Zeland Flax (Phormium tenax).
Tropicals can be brought into a bright sunny room and grown as houseplants until next spring arrives. However, there are a couple of challenges with this scenario. First, some of these plants have such high light and humidity requirements, unless you have a virtual greenhouse, don’t expect the same lush growth and flowering. Secondly, not many of us have such a room, especially with ample space for the larger specimens.
A more practical solution for many is to store them in a near dormant state in another part of your house or outbuilding. A cool dark place, one that stays above freezing at night and hovers ideally between 40 and 50 degrees during the daytime is ideal. Common choices include unheated basements and crawl spaces, root cellars, garages and potting sheds.
For this storage option, the objective is to keep the part that grows below ground from completely drying out or freezing while allowing the above ground growth to go dormant until next spring. Here are some of the particulars.
Plants that were growing in containers outdoors can be kept in their containers when moved inside to hibernate. Tropicals that have been growing in the ground can be dug up and potted or otherwise stored in a frost-free area.
Woody plants like hibiscus and angel’s trumpet should be carefully dug and repotted in a light potting medium. The soil should stay only slightly moist but be sure to check it periodically. Don’t be alarmed if most of the leaves fall off. The goal is to keep these plants alive but not necessarily stimulate new growth.
They can be left unpruned or you can cut back a bit to accommodate space requirements. Because they grow rapidly from new wood in the spring, heavier pruning and any fertilizing should be delayed until that time.
As you remove non-woody tropicals such as cannas, caladium and elephant ears, wait until after cold weather or frost has nipped the foliage and started the process of winter dormancy. There is no need to preserve the old foliage so cut it back to within a few inches.
These plants are easy to dig up and over winter. The source of next year’s growth comes from their bulbs, corms or tubers. For best results, allow enough time to rinse them clean and air dry before storing in a cool dark place as described earlier. Then place them in a container that is well ventilated, such as a crate or basket. Lay the bulbs in peat moss, sawdust or a similar substitute and space them so they are not touching each other. The material should be light enough to allow air circulation and retain just enough moisture to prevent the bulbs from completely drying out.
A month or two before next spring approaches, you can repot the bulbs for an early start to your spring garden, or wait until after the last frost and plant them directly in the ground again. Either way, over wintering tropicals is an easy, effective and economical way to keep your plants coming back better than ever year after year.
Joe Lamp’l
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