Texas encompasses a wide range of climate conditions from the moist coastal plains around Houston and Galveston to the parched expanses of the Chihuahuan desert. One thing they have in common is high summer temperatures. In the summer of 2008 the average highs in 19 of Texas' largest cities ranged from 90.8 to 99.4 degrees F. in June to 89.5 to 99.8 and 85.7 to 96.2 in July and August. Plants recommended for the Texas heat reward gardeners with multiple-season color and lower water bills.
Heartleaf rosemallow (Hibiscus martianus) is a small perennial shrub standing between 1 and 3 feet tall. Growing wild on the rocky hillsides and in the canyons of Texas and New Mexico, it possesses abundant, silvery heart-shaped leaves. This vigorous bloomer, a Lady Bird Johnson Wildflower Center Texas recommended plant, blooms even in midsummer when many other plants are resting. In areas of Texas where temperatures don't fall below freezing, it flowers all year.
Drought-resistant heartleaf rosemallow's 2- to 3-inch, red hibiscus-like blooms are hummingbird and butterfly magnets. Its small size makes the shrub a choice for containers as well as perennial beds, in full sun to part shade. Plant it in dry, well-drained limestone-rich soil: sand, loam and clay are acceptable.
Texas bluebonnet (Lupinus texensis), a heat-loving annual, is the Texas state flower. Wild plants bring masses of color to pastures and roadsides across the state between March and May. Texas bluebonnet's all-around performance has earned it recognition as a Texas Department of Agriculture Go Texan Superstar.
The blooms of the disease-and-pest-resistant wild plant have velvet-textured pale green leaves and dense spikes of deep blue flowers ascending to an eye-catching white tip. White and pink cultivars for home gardens are also available, according to the Texas Cooperative Extension. Plant the 1- to 2-foot annuals in slightly moist well-drained soil and full, hot sun. Once established in about two or three weeks, they are drought-resistant and will suffer or even die from excessive watering.
Autumn sage (salvia greggii) is a small, extremely drought-tolerant shrub that grows wild in southwest Texas' Chihuahuan desert. Standing up to 4 feet tall by 2 feet wide, autumn sage has a mounding habit and small, spicily-scented succulent leaves. Floridata suggests the leaves may be a water-conserving adaptation. Plants are evergreen where there are no hard freezes
Wild autumn sage produces white, salmon, red or pink flowers spires from spring to fall. Many cultivars are available commercially and some have purple or bi-colored flowers. Comfortable in the Texas heat, it's a good candidate for xeriscapes and butterfly gardens. Plant in full sun or part shade and well-drained soil. Established plants survive on the rainfall they get. Autumn sage should be pruned to prevent it from becoming leggy.