Overwintering Tropical Plants

Published: October 1, 2011

Container gardening has gained in popularity in recent years and tropical plants are well-suited for containers. Their lush growth and colorful flowers make them a welcome addition to the home landscape. Additionally, tropical plants seem to thrive in the heat and humidity of a typical Missouri summer. Many of these plants are woody species in nature that can grow quite large in a single summer and gardeners often are faced with the problem of what to do with them as the end of the growing season approaches.

The answer to this problem in certain cases is very simple. If the plants have become quite large and indoor space is limited or available light is poor, the easiest solution would be to allow the plants to freeze and start over with younger, smaller plants purchased from a local nursery or garden center the following spring. Young plants which are growing actively at the time of their purchase will most likely make more of an immediate impact in the landscape when compared with older plants that have been overwintered in less-than-ideal conditions. Since many gardeners become somewhat attached to their plants, allowing them to freeze is a difficult decision to make. Additionally, certain species of tropical patio plants can be a bit "pricey" and the prospect of replacing them each spring is unattractive.

For gardeners who have time and indoor space with reasonably adequate light and temperature conditions, it is possible to keep tropical patio plants for another summer of enjoyment. Plants fitting into this category include hibiscus, bougainvillea, mandevilla, banana, palm and citrus (orange, lemon or grapefruit). Since many tropical plants can suffer from chill injury, it is wise to move them inside for the winter when night temperatures start to consistently fall below 45 degree F.

Hibiscus are fairly content indoors and do not require a lot of space. It is wise to cut them back before bringing them indoors, but this will eliminate the flower buds that had developed on the growth removed. Smaller plants may be placed in a sunny window where they should bloom periodically throughout the winter. If a sunny location is not available, hibiscus can be placed in a cool location and allowed to drop their leaves and go dormant during the winter. The roots should not be allowed to dry out and, since the plant has no leaves, it will not require much water. A "rule-of-thumb" is to keep the root system "barely moist".

Bougainvillea is fairly ranked in growth habit and can take up a lot of space to overwinter. If the plant was in a hanging basket or small container, it can be cut back and placed in a sunny indoor location in a manner similar to hibiscus. Because many bougainvillea patio plants tend to be large containers, a more common overwintering method is to place it in a cool location that does not freeze and allow it to go dormant for the winter. Although its leaves will drop, bougainvillea is a woody plant that will initiate new leaves and growth when placed outdoors the following spring. As with hibiscus, the root system should not be allowed to dry out but do not over-water the plant.

Mandevilla is a very vigorous vine that will need to be severely pruned before moving it indoors. It, too, can survive in a sunny location in the home and might require additional pruning during the winter if growing conditions are good. Mandevilla also can be allowed to go dormant and placed in a cool location that does not freeze during the winter. Additionally, it can be overwintered by harvesting its thick, fleshy storage roots and protecting them from desiccation while keeping them cool. While requiring less space, this latter method usually requires more time the following spring before a blooming plant is established.

Bananas are probably the most difficult container plant to overwinter because of their size and high light requirement. Dwarf bananas are more likely to fit indoors and find a suitable home in a sunny window than are large bananas. If large bananas have produced side shoots, these shoots can be removed, potted and maintained as small plants throughout the winter. The shoots must have some roots present on the stem when cut since bananas do not root from the stem. An alternative storage method for large bananas is to cut the plant off and hold it in cool temperatures (45 to 50 degrees F). The cut stump will gradually die back to the soil and should be removed the following spring. When placed outdoors the following spring a new shoot may develop (in time) if the root system has been protected and not allowed to dry out.

Palms make useful houseplants as well as attractive patio or deck plants during the summer. They acclimatize rapidly to the lower light conditions found in the average home although some of the older leaves might yellow and drop. Watch for insects and mites that might have gained access to the plant while growing out-of-doors.

The various species of citrus all require about the same conditions for overwintering. If large, they can be pruned to accommodate an indoor setting. They require a sunny location, uniform moisture and a monthly feeding with a fertilizer that is acidifying in nature, such as those developed for azaleas. While they might flower given adequate light indoor, they seldom set fruit.

Regardless of the species, tropical patio plants moved indoors for the winter should be thoroughly inspected for pests. Mites are a very common pest of plants outdoors and are difficult to detect because of their small size. While they might not have developed into a major problem on the plant during the summer, the warm, dry conditions of the average home encourage their proliferation during the winter. Watch for leaves that are pale or look stippled and inspect with a hand lens. If present, mites can be eliminated by washing thoroughly with a mild detergent or spraying the plant with an appropriate pesticide labeled for use on mites indoors.

The end of the growing season does not have to signal the end of tropical patio plants that have brought months of enjoyment. With a bit of care they can be carried through the winter as "house guests" and put to work the following spring as outdoor patio plants.