Tropical ambiance

Coleus ‘Campfire.’ all ablaze. — milomingo/Creative Commons

Steamy heat waves seem to be a feature of our summers now and who could blame us for getting a little hot under the collar? At least we’re not living under a record-breaking heat dome - yet.

There’s no need to get into a debate over climate change. It’s clear from updated zone maps and recent temperature summaries that zone creep is real. Can we find a bright side? Sure – among gardeners who want to surround themselves with exotic plants of the tropical kind.

Not so long ago it was the lunatic fringe that insisted on pushing the envelope to grow palms, bananas, hibiscus, cannas and mandevilla vines 42 degrees north of the equator. Now we can find those plants in any garden center or home outlet. I get my patio palms at the grocery store, a sure sign that what was once edgy has now gone mainstream.

There’s something appealing, actually, about creating a small tropical paradise on the patio or around the pool. Surrounded by South Sea fragrances, Caribbean colors and foliage of Amazonian proportions, we can indulge in some latitude adjustment without leaving home.

Some tropical specimens are already familiar because we grow them as houseplants or annuals. Begonias hail from South America, dahlias are native to Central America and the ubiquitous impatiens comes to us from equatorial Africa. In fact, the core of your tropical collection might well be some hothouse species you’ve been growing indoors. Many appreciate a summer vacation under the trees and away from the arid chill of air conditioned rooms.

But the fun of choosing tropical species for the border or container garden is the chance to go wild and grow big. They don’t call the foliage plant colocasia “elephant ears” for nothing since individual leaves can reach 20 inches or more in length, and giant cannas can easily tower overhead at seven or eight feet tall. Supersized!

Bold color is another trademark of tropical species, in foliage as well as in flowers. The screaming scarlets of canna blossoms, the saturated orange and pinks of hibiscus and the exotic color mash-ups of fuchsias have little in common with the demure palette of the classic English border.

Elephant ear (colocasia) delivers bold color. — giennia/CC

Gaudy? We got gaudy. Sunglasses are required for some coleus, which manage a splashy variegation of pink, orange, red, yellow and purple – sometimes on the same leaf. It’s not a bad thing that we also have tropicals that cool things down a bit. The versatile chartreuse of certain sweet potato vines and the deep, dark, nearly black leaves of some colocasia make a great foil for companions on the sizzling end of the color spectrum.

Gardeners can plant clumps of cannas as back-of-the- border plants, use coleus as a groundcover or edge paths with smaller species like torenia, the wishbone flower. But tropicals often mix uneasily with plants of more temperate zones, which is why I think of them as ideal container specimens. Since tropical are commonly purchased as single plants and not in bunches, showcasing them in pots rather than swaths is also a matter of dollars and sense.

Tropical plants won’t tolerate cold, so setting them out late and taking them in early if they are to be kept over as houseplants is critical. Some, like cannas, caladiums and dahlias can be overwintered as tubers and planted again.

Through the growing season, these are thirsty and hungry critters. Water copiously and don’t let them dry out. Feed them regularly with a high phosphorus fertilizer formula like 10-50-15, with phosphorus the high number. Often they alternate vegetative and flowering cycles, so keep up the regimen for best results.

Be aware that there are a few tropicals that just won’t flower during the summer here in the north. Bougainvillea is one example – its natural blooming period is during winter months. Same for amaryllis. But with plants from every tropical climate around the world at our fingertips, this is a trifle. In the winter, there’s a better way to achieve tropical ambiance: Plane tickets.

Learn more

Two handy references are “Hot Plants for Cool Climates: Gardening with Tropical Plants” by Dennis Schrader and Susan Roth (Houghton-Mifflin Co.) and “The Exotic Garden: Designing with Tropical Plants in Any Climate” by Richard Averson (Taunton Press).