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US National Arboretum


Creating and Maintaining that Tropical Flair in Your Garden

Image of subtropical Hedychium coronarium, butterfly ginger

If you’d love to give your garden a “tropical feel,” but live in an area where the winter temperatures could dip well below freezing (USDA Hardiness Zone 7 and lower), take heart! You don’t have to construct a rainforest under glass in order to enjoy the bold look of these plants in your gardening space. Strict tropical plants can be difficult to overwinter in your house and expensive to replace year after year. If not carefully monitored while indoors, tropicals can become a feast for pests and diseases. Space constraints may also be a limiting factor when considering moving these plants inside for the winter. Therefore, growing subtropical plants—species that reside adjacent to tropical areas, but don’t experience tropical winters—may be just the cure for your tropical plant dilemma. They perform the same function as tropical plants in a design, but require a lot less space and maintenance during the colder months. A number of species may even overwinter in the ground, making your job that much easier. Following are a few examples of great subtropicals and how to take care of them during the winter.

Image of subtropical Japanese ginger
Japanese ginger, Zingiber mioga (shown at left), is reliably hardy in USDA Hardiness Zone 7 and has been reported to overwinter as far north as USDA Hardiness Zone 5. It is grown primarily as a foliage plant since its yellow flowers—which bloom well into late summer—appear near the base of the plant. In Japan, the edible flowers are harvested and pickled.

Image of subtropical ginger lily Two other late summer bloomers include the butterfly ginger, Hedychium coronarium (see image at top of article), and the spiked ginger lily, Hedychium spicatum (shown at right). The spiked ginger lily produces orange and yellow flower spikes and is native to the warmer provinces of China and Nepal, while the butterfly ginger produces extremely fragrant white blooms that flower into early October in Zone 7.

For any subtropical, the key to winter survival is “location, location, location.” In Zone 7 gardens—where temperatures rarely go below 0°F—subtropicals fair better in the ground when sited in a well-drained area close to the warmth of your house. If the plants sit in a cold, water-logged area for too long, the root system might rot. Several species may even survive a little farther north with some extra protection. Heavily mulching the plants and situating them along a south-facing wall will increase their chances of making it through the winter unharmed.

If you live north of Zone 7 and don’t want to chance leaving any of these plants outside, you can overwinter them in your house. After the first frost, but before the first freeze, plants in the ginger family can be dug up. Once they have been removed from the ground, cut off the foliage, pot up the root balls, and store them in a cool, dry area of your home. Watering is not necessary during the winter months as the plants will be in a dormant state. In the spring, when the plants start to grow again, you can move them to a warmer location in your house. Wait until the nights are consistently above 55° F before planting them back in your garden.

Image of subtropical Musella lasiocarpa In addition to the gingers listed above, the Chinese yellow banana, Musella lasiocarpa (shown at left), also creates a dramatic tropical feel in the garden. This banana family member produces many fragrant yellow flowers and grows between 4 and 5 feet tall. It can easily survive the winters in USDA Hardiness Zone 8, and marginally in Zone 7. Give this subtropical beauty a little extra winter protection in Zone 7 gardens by placing some type of caging material around the base of the plant and filling the area with leaves. If you live farther north, just cut off Musella’s top, dig up the whole plant, and place in a cool, dry spot in your house. Like the gingers, it won’t need watering. In the spring, you can treat it the same as the gingers.

In just a few simple steps, you can keep your garden a “tropical paradise” year after year without the headache of keeping big plants alive in your home. For more examples of subtropicals grown at the Arboretum, please visit the Asian Collections, the Introduction Garden, and the National Herb Garden.

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Last Updated   November 7, 2006 10:44 AM
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