If you admire the look of tropical plants in the garden but live too far north, you can bring the tropics to your garden with hardy banana plants (Musa basjoo) and Chinese windmill palms (Trachycarpus fortunei) in the temperate zones of 7 and 8 in British Columbia, Southwest Ontario and parts of the Maritimes.
Although these plants are tough cookies and can be left outside all year long in the warmer parts of Canada, they still need winter protection. If they are not too big, bring them inside and use them as houseplants. Place in front of a sunny window and water when needed. Don’t keep them too dry as that promotes spider mites, whilst keeping them too wet promotes rotting. If you don’t want to use them as houseplants, an alternative is to store them in a basement with grow lights, in a heated garage or greenhouse. Check on them often to make sure they are not too dry, too wet or having health issues.
If your container grown banana or palm trees are too big to bring inside, there are ways to protect them. Container grown plants are more prone to winterkill since their roots are in pots and are not protected by the thermal heat of the earth. If you can bury their pots in the ground, do so, or wrap the pots with insulation, layers of cardboard, carpets, anything that will insulate them from the cold, the wind and temperature fluctuations. Place at least 6 inches of leaves, mulch, straw or even soil over the crowns (where the stem meet the roots). Follow the rest of the instructions below to protect the upper portions of the plant
Protecting Banana Plants outside
There is no need to try to protect banana stems as they are just temporary anyway. Technically, banana plants are herbaceous perennials, which means they are non-woody. New stems arise from the underground rhizomes (similar to bamboo, iris and grasses). Once the new stems produce fruit the stem collapses and dies, so don’t panic when this happens; it will be replaced soon enough. Therefore we are not trying to protect the stems, but the roots. As long as the roots are alive, new shoots will energetically emerge in spring.
To protect their roots/rhizomes, cut off any stems and cut them into 1 foot pieces. Surround the root area with a cage made of chicken wire or hardware cloth to make a tube a few feet high or higher. Lay cut up banana stems and leaves of top of the roots inside the cage. Add more layers of fall leaves or straw if you wish. If they are located in a sheltered location where they don't receive rain, check on them often to make sure they are receiving adequate water. Plants drying out during the winter is just as bad as sogging out too wet
Protecting Palm Trees outside
The most tender and important part of a palm tree is the central bud that grows at the very top of the plant. If that dies, so does the rest of the plant no matter how toasty warm the roots are. That central bud is where all the new foliage originates from. An easy way to protect that growing tip is to gather the surrounding fronds and tie them together over the bud. Continue to wrap with many layers of burlap, cloth or other breathable fabric. Don't wrap too tightly though as this reduces the insulating effect of the fabric.
Protect the crown and roots with at least 6 inches of organic mulch such as leaves, straw or wood chips. Wrap the base and trunk with a breathable fabric, fiberglass or even cardboard. If the palm is small, protect it with a cage as mentioned with the banana. For a simple fix, tie the top fronds together with twine then wrap them with non-LED Christmas lights. The heat from the old fashioned lights should keep that central bud adequately warm.
Rain & Rot
In our rainy climate of the Pacific Northwest, the fear of plants becoming rain sodden and rotting underneath their winter protection is a concern, so they are often put under the eaves away from the rain. This is a good idea as they also receive protection from the house, however, if the soil dries out, this also promotes winter damage. Check on them occasionally and add water if and when it is needed.
Plastic is often added on top of insulating fabric or even used alone to keep the relentless rains from rotting the plants, however, since plastic doesn’t breath, it holds any moisture in. This actually promotes decay and has little insulating value. To prevent soggy fabric, place plastic over top of the fabric etc., but poke a many holes in the sides to let air flow.
Good luck with your tropical plants this winter. Cross your fingers that Old Man Winter will be kind to us.
Here are some of my previous blog postings. They cover a wide range of topics from bugs to my botanical excursions and conventions. Click on whichever interests you on the titles below for easy navigation.