Sizzling Summer Foliage Plants
by Allan M. Armitage

Beat the heat in colorful fashion with these annuals and tender perennials that offer flamboyant foliage for summer containers and borders.

For many years there was not much available for mainstream gardeners other than coleus, and it was a bit of a wimp, mostly relegated to shade. That is not to say that people were not using burning bush (Kochia spp.) or calico plants (Alternanthera spp.) somewhere; selections simply were not widely available.

Times have certainly changed. Today, growers can’t keep up with the demand for new foliage plants, many of which turn out to be reformed hippie house plants.
I believe this transformation of foliage plants from Clark Kent to Superman began in the early 1990s, when the first series of Sun Loving coleus was introduced. As gardeners and landscapers discovered them, there was no turning back.

Perhaps that alone would have been enough to propel foliage plants into the mainstream, but the final impetus came with, of all things, the introduction of a culinary plant—the sweet potato. When ‘Blackie’ was first mentioned as a potential garden plant, people scoffed, “Who could make money selling a sweet potato?” The introduction of chartreuse-leaved ‘Margarita’ a year later resulted in sales that were nothing short of superheroic.

After that, old-fashioned plants like burning bush, bloodleaf (Iresine spp.), and copperleaf (Acalypha spp.) were dusted off, new cultivars were introduced, and suddenly these old plants became new again. Purpleheart (Tradescantia pallida ‘Purpurea’) and piggy-back plant are now available as outdoor plants, Rex begonias have been transformed into trendy container items, and cast iron plants are as common in southern landscapes as kudzu.

Color has always been the defining characteristic for garden plants, and it accounts for the huge resurgence of interest in foliage. This ascendency has also been supported by the ease of nursery production, and by the relatively low maintenance needs of these plants.

Choosing Favorites

In my roles as a horticulture professor, trial garden coordinator, and writer, I have been growing, researching, and introducing foliage plants for many years, with an eye for those that are heat and drought tolerant. At the University of Georgia’s Trial Gardens in Athens, we cannot keep up with all the new introductions. When asked which are my favorites, I rub my chin and constantly change my mind depending on what we have been trialing recently.

Inevitably in articles or presentations there’s insufficient space or time to include more than a handful of my favorites from different genera. But here are a few of my top picks. My apologies in advance for leaving out any of your favorites.

Calico plants (Alternanthera spp.)

Originally made popular by Victorian gardeners, calicos made their debut as fillers for containers, then later found a function as edging plants. ‘Red Threads’ is still hard to beat as a colorful edging or groundcover plant, and recently ‘Royal Tapestry’, even shorter, with a more subdued color and excellent vigor, appeared on the scene as well. For a bold multicolored look, I like ‘Brazilian Red Hot’. ‘Crème de Menthe’, with its white and green foliage, is a little easier on the eyes. When I need consistently dark foliage all season to contrast with brighter colors, however, I opt for ‘Gail’s Choice’.

Most calico plants grow best in full sun, but I have found the Party series, especially ‘Party Time’, to be highly tolerant of shady areas while still providing handsome color. Heights vary from six to 12 inches—for groundcovers—to two to three feet.

Ornamental Sweet Potatoes (Ipomoea batatas)

With the advent of ‘Margarita’, which is still one of my favorites, the breeding of ornamental sweet potatoes began in earnest. What the sweet potato introductions accomplished was to provide quick growing, colorful fillers and spillers ideal for containers and mixed beds. ‘Blackie’, ‘Margarita’, and ‘Tricolor’ were the building blocks, followed by at least a dozen more introductions in the last five years, including one of my newer favorites, ‘Bewitched’, which has shiny, deep bronze foliage. It is part of the Sweet Caroline series.

I used to think I could use them in mixed containers, but they grow so vigorously they often eat their roommates. They revel in heat and humidity, but perform admirably in almost every part of this continent.

Coleus (Solenostemon spp.)

Asking a gardener to name their favorite coleus is like asking a chocoholic for their favorite sweet. The market has exploded so much in the last 10 years that it is almost impossible to choose only one or two.

If I have trialed one, I have trialed 500, and there are very few I would not recommend to my daughters, who simply don’t have time to figure out which is which. The main limitation to anyone’s recommendations is locating the cultivars, because retailers seldom stock a wide selection. If possible, take some cuttings of your favorites in the fall (they root like… well, coleus) and keep them in a sunny window over the winter.

One thing that should be made clear is that most coleus today are adaptable to full sun as well as part shade conditions. The colors will be more intense in the sun, but less water will be required in shadier conditions. Do not fertilize heavily or some of the colors may fade.

Waffle Plants (Hemigraphis spp.)

I have had a long like affair (love affair may be a little strong) with these interesting little plants, whose common name derives from the wavy indentations on the leaves. In general, waffle plants have deep green leaves and small, white flowers but the cultivar ‘Black Wizard’ has spotted purple leaves with purple undersides. I enjoy this selection, but find it a little harsh on hot summer days, which is perhaps why I so enjoy the calmer multicolored foliage of ‘Moonlight Improved’. The muted silvery green and purple leaves serve as a soothing groundcover in garden beds.
Growing no more than six inches tall and spreading slowly, these plants are best viewed up close. They make ideal “fillers” for border edges, rock gardens, and containers in full sun to part shade.

Red Shield Hibiscus (Hibiscus acetosella)

Most people equate hibiscus to plants with dinner-plate sized flowers, and as beautiful as many of them are, there are a number of wonderful hibiscuses whose foliage is stunning throughout the summer. The selection ‘Panama Red’ is particularly satisfying because the lustrous red foliage never fades no matter the summer temperature.

Plants can be cut back once in the spring and the subsequent branching results in full bodied plants all season. They will grow six to eight feet tall with an upright form, but will only flower in areas that do not experience frost. They are fully perennial in USDA Zones 9-11.

The author of more than a dozen garden books and CD ROMs, Allan M. Armitage is a horticulture professor at the University of Georgia in Athens.

Photo credits: Alternanthera ‘Party Time’ and Hemigraphis ‘Moonlight Improved’ both by Allan M. Armitage

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