At home in the Tropic of Maryland

Tropicals: New breeds of warm-zone plants bring visions and aromas of paradise right to your back yard

In The Garden


Maryland gardeners have always grown some tropical and subtropical plants during warm weather, then brought them inside for the winter or left them outside to be blitzed by the first hard frost. Gardenias, tropical hibiscus, dahlias, begonias and caladiums belong in this category of familiar and reliable tropical plants. Now we're introducing more new plants from the Torrid Zone into the garden or at least onto the patio. And plant breeders are producing strains of traditionally tropical plants that are hardy in colder zones such as ours (zone 7).

Generally speaking, tropical plants should be put out in May, like tomatoes. They should be planted in a lot of compost and be kept moist but well drained.

Lily of the Nile (Agapanthus) is an example of the trend to breed hardier tropical plants. Agapanthus has tall blue or white clusters of lily-shaped flowers and is a popular patio plant because it blooms for 60 days. Now there is a hardy cultivar, 'Midnight Blue,' whose bulbs can tolerate being left undisturbed during our winters.

You may have seen Peruvian lily (Alstroemeria) for sale in the supermarket as a cut flower. It ranges from 18 to 30 inches, blooms from June to September in bright pink, red, yellow, pink and purple. It is often spotted or streaked and provides an exotic and profuse addition to the Maryland flower bed or container. In the past, Alstroemeria have required being dug up and wintered over in the basement, like dahlias, but new varieties are hardy in zones 6 and 7. Their tubers are available in many horticultural catalogs.

Many of us enjoy potted amaryllis at Christmas time. Some of us may also know the South African Amaryllis belladonna as Naked Lady, so named because its straplike leaves come up and die down in the spring and then its tall pink flowers spring unadorned in late summer. The bulbs are rodent-proof and usually survive our winters if heavily mulched.

Also, while we're familiar with tropical hibiscus that collapse with the first frost, never to return, there are also some hardy herbaceous hibiscus, such as the species H. moscheutos. They are also called rose mallow. Recommended cultivars are 'Disco Pink,' 'White' and 'Red' and 'Lord' and 'Lady Baltimore.' Their flowers are the size of dinner plates.

For those determined to have a truly tropical look, there are a few ginger plants (of the 1,300 species of ginger) that are hardy to zone 7. Your best bets, according to the Stokes Tropicals catalog, are probably Alpinia formosana 'Pinstripe,' Curcuma petiola 'Hidden Lily' or Curcuma petiolata variegated 'Emperor.' Gingers add an authentic tropical (and often spicy) component to the garden.

Still, most tropical plants are not hardy here and are best used to provide a temporary exotic touch to the garden. A dramatic new foliage plant is Persian shield (Strobilanthes), which has long pink and purple leaves coated with a bronze iridescent sheen. And while many people consider lantana an annual, it is really tropical, which I realized when I saw one in Majorca years ago; it was over 15 feet tall, an impressive sight of clusters of red, yellow and pink flowers. They grow to about 2 feet here, and their leathery leaves smell of lime; perhaps that's why deer avoid them.

Finally, Mandevilla, a tropical vine, is popular here for its large hot-pink flowers and because it grows so fast. In one season, it wraps itself around posts and trellises and blooms vigorously, making a lush exotic show, which is what tropical plants do best.



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