Thanks to their pretty blooms and easy culture, ruellias have made their way into lots of flower beds. Though most common in Texas, they’re quickly making inroads into the rest of the South, especially among gardeners who want lots of bloom with little fuss. The flowers resemble small, thin-textured petunias. These plants resist damage by browsing deer. Depending on the variety, Ruellia ranges in height from 8 inches to 4 feet.