Mexican petunias are faithful ornamentals that can be counted on to bloom throughout our summer Texas heat. Mexican petunia, Ruellia brittoniana (roo-ELlee- ah brit-toe-knee-AN-ah) isnativetoMexicoandSouth America. It is a hardy ornamental that thrives when planted in well-draining soil and full sun. It is a shrubby herbaceous perennial that, at maturity, grows to 3 feet in hei...