Flowers and Shrubs & the heat of summer!

This article appeared in the Arkansas Democrat Gazette on 7/2/11 – I wanted to capture it here for reference sake so that we might make some intelligent decisions for our backyard garden when we’re ready to plant.

Turn up the heat! These plants will thrive when summer sizzles
STORY AND PHOTOS BY JANET CARSON

You know the saying, “If you can’t take the heat, get out of the kitchen.” The same goes for an Arkansas garden: If plants can’t take the heat, they shouldn’t be there!
Summer has already been a scorcher, as well as dry in most areas of the Natural State. Rainfall has been spotty at best. Even for gardeners who are diligent in their watering, some plants seem to be faring better than others.
Color in the garden is something most gardeners strive for every season, whether blooming shrubs, perennials or annuals. When choosing plants for the landscape, consider their season of interest and how adaptable they are.
The first step is to look at the USDA climatic zone map, by which plants are rated for their hardiness. We have three such zones in Arkansas. The bulk of the state is Zone 7 (average low winter temperature of zero), while south Arkansas is Zone 8 and north Arkansas is Zone 6. Keep in mind the only piece of information you get from this hardiness zone map is the average low winter temperature. It doesn’t tell you anything about summer heat, rainfall or humidity.
So use this as a guide, not as your gardening bible, because while many plants are rated for our climatic zones, some aren’t as tolerant of summer as others. Still, we do have a wide range of plants that can take the heat. Some require ample water, while others withstand hot and dry conditions.
SHRUBS, SMALL TREES
Few plants are as associated with the South as crape myrtles and most are thriving, even in this summer’s weather. They not only take heat, but do well in dry conditions. The more sunlight they get, the better they like it. While they are drought tolerant, a little extra water can go a long way in helping them with their flowering ability. Deadheading (cutting the spent flowers) can also put more energy into new blooms.
Other shrubs and small trees that are blooming now include Vitex, or chaste tree; Buddleia (also spelled Buddleja), or butterfly bush; Althea, or rose of Sharon; and summerflowering spireas. Abelia has been around for a while, and keeps on blooming regardless of the weather. New varieties give you options on size and foliage color.
Our native Clethra, or summersweet, is blooming now in sun to partial shade and has fragrant flowers which are quite attractive to bees and butterflies.
NATIVE PLANTS
Speaking of native plants, because they rely on Mother Nature to water them, they have to be tough to survive an average Arkansas summer. Some natives that are blooming now include the spiky perennial Liatris, or gayfeather; the lovely orange butterfly weed, Aesclepias tuberosa, with its strong taproot; and Echinacea, or purple coneflower.
Nativars and improved cultivars of our native species are readily available at many nurseries and garden centers. With Echinacea, if you don’t like the native pink variety, they now come in red, orange, white and yellow. Coupling a little moisture and fertilizer with deadheading encourages them to bloom for months.
Gaillardia, or blanket flower, is a tough Oklahoma native that loves hot, dry weather. So does Gaura, with a summer-long explosion of pink and white flowers. Goldenrod is a long-lived perennial with a long season of flowering — and no one is allergic to it, even though it is often blamed for hay fever instead of the real culprit, ragweed. The hotter and drier it is, the happier the goldenrod is. And don’t forget sunflowers. The native saw-toothed sunflower blooms a long time, but give it room since it can grow quite tall.
OTHER PERENNIALS
Other perennials with long staying power include Ruellia, or Mexican petunia; yarrow, with a wide array of flower colors; old-fashioned Crinum lily, which is also winter hardy in at least half the state; and the long-blooming catmint (Nepeta x faassenii).
Agastache is another great perennial with lots of colors to choose from. It blooms all season, and bees and butterflies love it. Monarda, or bee balm, and almost all of the ornamental grasses tolerate heat and drought.
SUCCULENTS, SILVER LEAVES
Succulents are plants that have thick, fleshy leaves. Just by their appearance, you know they can take dry conditions. Some are groundcovers and others grow 2 feet tall. Hens and chicks, Sedums and Euphorbias are proven performers. Yuccas and cactus can also take very dry conditions, but make sure they fit the style of your landscape.
Silver-foliage plants are another group of plants that give you clues to their heat adaptability by their appearance. Lamb’s ears, Artemesia, dusty miller and old-fashioned rose campion prefer poor, dry sites. Too much water and they fade away. They also do very well in hot conditions.
TROPICAL
Tropical plants love heat and humidity, so are quite at home in the summer garden in Arkansas. While they won’t survive winter outdoors, they can be protected inside or carried over in a protected garage or storage building.
Or you can simply buy new plants every season. Since they basically bloom from the day you buy them until a killing frost, they are a good source of color, so a great investment, even if just for one season.
Hibiscus, Bougainvillea and Mandevilla are popular and have been around for years but try some of the more unusual ones that grace our markets: Jatropha has clusters of pink flowers, while Ixora has clusters of yellow or orange flowers. Tibouchina has large, velvety purple flowers while Plumeria has fragrant, large flowers in a wide range of colors and esperanza is a sea of yellow all summer. Mandevilla is usually associated with hot pink flowers but now comes in white, red and several shades of pink.
While most tropical flowers do best in full sun, there are some that will take the shade. Chrysothemis, or “Black Flamingo” flower; Plectranthus “Mona Lavender”; butterfly Clereodendron; and bromeliads can add color in the shade. Remember, because most tropical plants are grown in pots, they need regular watering and fertilization because frequent watering leaches nutrition.
HOUSEPLANTS
Most of our houseplants are also tropical plants, albeit grown more for their foliage than flowers. They can make great accents in the shade garden. Everything from Dracenas and Philodendrons to mother-in-law’s tongues (or Sansevieria), arrowhead plants and Chinese evergreens can be planted in the ground for the season, or their pots can be interspersed in the outdoor landscape.
Croton is a great houseplant for seasonal color in full sun. The more light it gets, the more color the foliage has, and it blends beautifully in fall gardens with its array of orange, yellow and red foliage. And we now have a wide selection of palms, some hardy and some not, that can give a tropical feel to the landscape. Bananas in standard and dwarf sizes are also showstoppers in the summer landscape. New varieties are now winter hardy statewide, but don’t produce bananas.
SUMMER ANNUALS
And last, let’s not forget summer annuals. Annuals have to be planted every season, but they give a great deal of color for relatively little care. Some are more heat tolerant than others, and water needs vary. Some of the most heat-tolerant varieties include Lantana, Pentas, Angelonia (summer snapdragon), Melampodium, periwinkle, Cosmos and sweet potato vine. Coleus and Begonia can take sun or shade, and Impatiens and Caladium thrive all summer if they get ample moisture.
Petunias and Callibrachoa will bloom all summer, if you keep them well fertilized. If you don’t, you won’t have constant color. If summer annuals get leggy, pinch them back, fertilize and water and they should rebound, lasting until a killing frost. If you forget to water and they burn up, replacements are still available at local nurseries.
VISIT GARDENS, NURSERIES
Visit other gardens or botanical gardens to get ideas. If they are doing well now, think how well they would do in a milder season. Keep a journal or a list of plant ideas. Visit nurseries even in the summer. The great thing about being a gardener is you can never have it all. There is always a new variety or cultivar on the horizon.
To learn more, plan to attend the Aug. 4 Rice Expo at the Rice Research and Extension Center, 2900 Arkansas 130 E. in Stuttgart. “Plants that can take the heat” is the last topic in a jam-packed day of events with everything from rice information to cooking, insects, diseases and plants. It all begins at 9:30 a.m. For more information, contact your local county Extension office.

Althea, or rose of Sharon, a shrub

Bougainvillea, a tropical plant

Asian moon Buddleia, a shrub

Lamb’s ear, a silver-leafed plant

Echinacea, or purple coneflower, native of Arkansas

Butterfly weed, native of Arkansas

Ixora, a tropical plant

Coleus, summer annuals

Pink Cosmos, summer annual

Double purple Althea, a shrub

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