Melampodium. A mass of yellow daisy-like flowers and bright green foliage makes this annual a welcome sight in the summer garden. Melampodium reseeds readily. You'll want one of the compact cultivars such as 'Million Gold', shown here, 'Derby' or 'Showstar' (slightly taller). Give this plant average soil and expect bloom from late spring to early fall.
Angel's trumpet. Whether they're growing in the ground or in a container, the gigantic trumpet-shaped flowers and large leaves of Brugmansia add a dramatic, tropical look to the garden.
Vinca. Prolific, non-fading flowers, ultra-clean foliage plus high heat and drought tolerance are the trademark of annual vinca (Vinca or Catharanthus roseus). A great low-maintenance plant for bright color all season in the ground or in containers.
Profusion series zinnas. Regular garden zinnias come in a wide range of colors but are subject to disease and insect problems, especially powdery mildew. The narrow-leaf zinnia (Zinnia angustifolia) has high pest resistance but limited colors and small flowers. A cross between the two resulted in the Profusion series, which exhibits the best of both excellent resistance to diseases and insects and more colors than its narrow-leaf parent. First to come out were Profusion White, then Cherry and Orange, then Apricot and Profusion Fire. These zinnias bloom profusely and robustly, even in the heat and humidity of the Deep South. They grow 2 feet tall and wide and don't need to be deadheaded.
Love-lies-bleeding. Long red or maroon tassels of flowers appear on this heat-tolerant annual (Amaranthus caudatus) in the summer. The blooms hold their color after cutting and are prized by crafters. Grows 3 to 5 feet tall; reseeds.
Cuphea. Gardeners who have very hot summers appreciate many of the options in the family of cupheas. Heat tolerance is very high for most. Tubular red flowers attract hummingbirds. Size and habit vary according to species. USDA Zones 10 to 12. Very frost sensitive; dies to the ground in Zones 8 and 9 but usually grows back quickly in spring. Other cupheas that are great for heat: Mexican heather (C. hyssopifolia), batface cuphea (C. llavea), candy corn (C. micropetala) and giant candy corn (C. melvillea). Pictured: The cigar plant (C. ignea) has dark green pointed leaves and a tightly branched habit to 12 inches tall.
Rudbeckia No doubt about it, almost any black-eyed Susans and there are lots will make you look like a great gardener. Robust plants put on a show of daisy-like blooms, especially in the summer's dog days, tolerating both heat and drought. Try 'Cherokee Sunset', a mix of yellow, orange, rust and dark red; 'Becky Cinnamon Bicolor' ('Becky' also comes in yellow, orange and a mix); or 'Prairie Sun', which has green centers.
Mexican sunflower. Three-inch, bright orange flowers on a medium-green bushy plant recommend this annual for gardeners looking for heat tolerance. T. rotundifolia averages 4 to 6 feet tall. Attracts butterflies and hummingbirds. Self sows.
Eustoma. A welcome color for a hot garden, eustoma (Lisianthus) produces lots of 2-1/2-inch-wide purplish flowers on densely branched, 12-inch plants. 'Forever Blue' earned an AAS award in 2001. 'Forever White' is another winning selection. Deadhead to increase bloom.Image courtesy of Proven Winners
Strawflower. Perfect for hot, dry places in the yard, this annual forms a low mound about 6 inches tall, with a cap of bright yellow flowers covering the gray-green foliage. Provide water until plant is established; after that, little to no supplemental irrigation is needed. (Pictured: Flambé); image courtesy of provenwinners.com
Mandevilla. This tropical vine loves heat and humidity and will send up a huge bouquet of beautiful flowers over a trellis, a beautiful summertime asset, even if you live in a colder climate and can't overwinter it.
Blanket flower. This striking plant regularly appears on lists of heat-tolerant plants; there are many great cultivars so you have only to choose your color. A 2011 All-America Selections winner, Galliardia 'Arizona Apricot' forms a foot-tall mound topped with large flowers that are a bit lighter in color than most blanket flowers. Photo courtesy of All-America Selections
Moss rose (Portulaca). A great choice for sunny, hot, dry areas where you want color, this succulent blooms when the sun is shining, the flowers closing in midafternoon and on cloudy days. Look for the Sundial Series portulacas, which stay open longer each day. Moss rose blooms from spring till frost.
Lantana. The bright flowers, clean evergreen foliage and drought tolerance make this Southern perennial (or shrub) a stalwart of gardens in hot, dry areas. One to 6 feet tall, low and spreading to upright (depending on variety), lantana comes in yellow, orange, pink, red and bicolors. Attracts butterflies, and birds eat the berries. USDA Zone 8 to 11. Notes: The leaves of some types are poisonous to humans and animals. Invasive in Hawaii, central and southern Florida.Image courtesy of Proven Winners
Aloe. In addition to occasional flowering, these heat- and drought-tolerant champions also offer foliage texture and color in the garden.