Perennials for Heat

Lemon Verbena

• Lemon verbena (Aloysia triphylla) is a perennial shrub appropriate for plantings in U.S. Department of Agriculture plant hardiness zones 8 through 10. This includes states such as Georgia, California, Nevada and California. Lemon verbena, native to Chile and Argentina, grows to 15 feet in its wild settings, but usually to 4 feet as a container plant. Its white flowers bloom during July and into September. The glossy, green foliage gives off a lemony scent.

Four O'Clocks

• Coming form the tropical habitats of South America, the four o'clock plant (Mirabilis jalapa) is at home in the heat. Use four o'clock plants as far south as USDA zone 11, where they will grow in full sun and turn out flowers of multiple colors all summer long. Four o'clocks grow to 3 feet, spread out 2 to 3 feet and resemble many-branched shrubs. The perennial can spread into the surrounding countryside, warns Floridata, and all portions of this species are toxic if ingested.

Butterfly Lily

• Humid, hot summers are no problem for the butterfly lily (Hedychium coronarium), a tropical perennial that hails from nations such as India. Butterfly lily attains heights up to 6 feet, blooming in shade or full sun. Butterfly lily has large leaves, with some as long as 24 inches. Plant this perennial in a tub or container, keeping its roots moist, and place it near ponds and other wet locations. The flowers are not particularly attractive to butterflies, but resemble them in their form, hence the plant's name.

Pale Purple Coneflower

• Drought conditions, heat and humidity do not deter the pale purple coneflower (Echinacea pallida), a species native to the eastern United States and capable of growing as far south as USDA zone 10. Pale purple coneflower handles poor quality soils, doing well in full sunshine. The perennial produces a light purple flower during June and July on a straight, hairy stem as tall as 4 feet. Pale purple coneflower works as part of a native plant garden, cottage garden and in wildflower meadows, according to the Missouri Botanical Garden.