Ruellia brittoniana (Mexican Petunia) is a shrubby perennial boasting a profusion of petunia-like, vibrant lavender-blue flowers, 2 in. across (5 cm), from midsummer to fall. Borne solitary or in clusters at the tips of purplish stems, they rise above the foliage of lance-shaped, glossy green leaves.
Mexican petunia plant is very hardy able to survive drought as well as flooding. The best approach is for watering just enough to keep the soil consistently moist. While these plants are sturdy and can go without water for a long time, young petunia ruellia simplex needs regular watering.