By Dan Gill
LSU AgCenter Horticulturist
(07/15/16) If you regularly read national gardening magazines or get a variety of gardening catalogs, you may have noticed that tropical-look landscaping is a trend that is gaining attention across the country. To Louisiana gardeners, this hot concept is old hat. We’ve been gardening in the tropical style as long as anyone can remember. But there is almost always room to try one more plant, and many great tropicals are out there for you to purchase and plant in your garden now.
In addition to their amazing heat tolerance and outstanding summer performance, we grow tropical plants for a variety of reasons. Some plants, such as hibiscus, ixora, canna, angel trumpet, bird-of-paradise and butterfly ginger, are grown for their beautiful, and often fragrant, flowers. Others, such as peacock ginger, caladium, elephant ear and copper leaf plant, are grown for their attractive, colorful foliage. The best tropicals are those that reliably survive winters where you garden. Despite their tropical origins, many are hardy throughout Louisiana if given some winter protection.
Gardeners who are working with shady areas will find a gold mine of shade-tolerant plants among the gingers. In their natural habitats, most gingers grow under the canopies of trees in filtered light, although some grow in the open at the edge of water and in sunnier conditions. Generally, gingers will do best where they receive direct sun for about two to four hours a day and should not be planted in hot, sunny, dry locations. Shell ginger and some types of Curcuma and Costus will, however, grow in full sun.
Many different gingers can fill a variety of gardening needs. Low-growing gingers, like peacock ginger and smaller species of Curcuma or Globba, make great ground covers or clumps at the front of shady borders. Medium-sized gingers 3 to 6 feet tall include species and cultivars of Curcuma, Hedychium and Costus, while the shell ginger grows 10 to 12 feet tall. These larger gingers are excellent choices for accents, screens or the back of a border.
No other summer-flowering shrub surpasses the tropical hibiscus (Hibiscus rosa-sinensis) for glossy, dark green foliage and nonstop flowers in shades and blends of pink, yellow, orange, white, lavender or scarlet. The long blooming season runs from late spring through November or later.
The tropical hibiscus thrives in sunny locations and looks great in beds or containers. It is one of the more tender tropicals and will not reliably survive temperatures below the mid-20s. Still, they are readily available and not too expensive, so it’s easy enough to replace any lost to winter freezes. If grown in containers, you can move them to safety on cold winter nights.
We grow a number of species of clerodendrum for their beautiful, fragrant flowers and, in some cases, ornamental fruit. They may freeze back during especially cold winters but reliably return from their roots.
Perhaps the most well-known is the cashmere bouquet (Clerodendrum bungei). Effortlessly easy to grow in part shade to shade, cashmere bouquet produces 4-to-5-foot-tall stalks with large clusters of small, fragrant, mauve flowers. But it spreads rapidly.
Many of the clerodendrums produce stems that run underground and produce plants some distance from the original plant, but none are quite as bad as cashmere bouquet. If you are aware of this habit and promptly remove sprouts from areas where you don’t want them, this is not a problem. But if you are the type of gardener who isn’t inclined to keep a careful eye out and remove them as necessary, you probably shouldn’t plant those that spread rapidly.
One of the best clerodendrums is the harlequin glory bower (Clerodendrum trichotomum). This large shrub to small tree looks as tropical as the rest, but in fact it is quite hardy. It drops its leaves in winter but doesn’t freeze back. Starting in June or July, large clusters of very fragrant white flowers last until August. Then amazing turquoise fruit continues the display. It spreads rapidly.
Brugmansias are large-growing, tree-like plants often reaching heights of 10 feet or more if winters are mild. The large leaves are generally about 8 to 12 inches long and are covered with fine hairs. They are easily grown in a moist, fertile, well-drained soil in full sun to part shade.
The common name for Brugmansia is angel’s trumpets. The trumpet-shaped flowers are large – about 9 inches long flaring to about 6 inches across – and may be white, yellow, pink or peach. A tree in full bloom is covered with these dramatic funnel-shaped flowers hanging down from the branches as if trumpets directed at the earth from the heavens above.
The fragrance is outstanding. Most noticeable in the evening, the soft, seductive scent floats in the air like expensive perfume with light lemony overtones. To stick your nose right in a flower and take a whiff is almost intoxicating.
Including tropicals in the landscape has many rewards, but you do need to be prepared to protect them when and if necessary during winter. And you’ll occasionally lose tropicals during unusually cold winters. When they perform like troopers with beautiful flowers and foliage through the hottest part of the summer, however, many gardeners consider it well worth the effort.
Angel trumpet. Photo by Tom Pope
Hedychium gardenerianum ginger. Photo by Tom Pope
Hibiscus rosa-sinensis. Photo by Tom Pope