About 300 species of bananas belong to the Musa genus. Of these, only 20 hold commercial interest to growers. Banana trees grow well in the tropics where the average temperature is 80 degrees Fahrenheit. At least 3 1/2 inches of rain fall each month in these areas. Hobbyists hoping to cultivate bananas outside the tropics must carry out proper winter care of banana trees to prevent the early demise of the plants.
Understand banana trees’ temperature requirements. Temperatures for the best plant growth conditions are between 79 and 82 degrees Fahrenheit, while the most favorable temperatures for fruit production range from 84 to 86 degrees Fahrenheit. At about 50 degrees Fahrenheit, all growth ceases and tissue death may set in. At 28 degrees Fahrenheit, the above-ground plant dies completely.
Winterize the banana tree trunks. Clip off the leaves and place plastic mesh around the banana tree trunks. Leave a 15-inch radius around the trunks. Fill the diameter spaces with dried leaves and cap the mesh with plastic sheets. This provides trunk insulation during the winter.
Protect the underground corms from frost. If it is not possible to shield the banana trees from winter temperatures, protect the subterranean corms with a thick covering of mulch. This covering insulates the ground and protects the corms and their root systems from frost damage. Banana trees may grow back—even if the above-ground structures died—as long as the corms did not suffer tissue death. The dwarf Cavendish is among the cultivars most likely to suffer in cold weather, while the dwarf Walha is much more cold-tolerant.
Guard the banana trees against winter wind damage. Even if it is inevitable that the above-ground plants die back due to cold temperatures, protect the plants from severe wind damage. Wind speeds of 40 miles per hour not only topple the trees but also damage the subterranean corms and their roots. Erecting an artificial wind break barrier from plastic netting is a good option. Wind it around sturdy poles--anchored securely to a building or into the ground—and divert the wind force to help protect banana tree structures below ground.
Wrap tree wrap around younger plants. Tree wrap offers frost protection for smaller banana trees during a brief cold snap. This makes the practice especially important if the banana tree survived the entire winter and has begun to grow again, but now faces the threat of a late frost. Lessen irrigation when anticipating a cold-snap, since cold and wet soil leads to banana root rot.