Mexican Petunia

Mexican Petunia (Ruellia simplex)

Mexican Bluebell

Full sun to part shade, medium to dry moisture level, tolerates a wide range of soils including clay, moderately acid to neutral pH.

2–4 feet tall, blooms from early summer through frost with purple, pink, or white trumpet-shaped flowers; spreads aggressively by both rhizomes and explosive seed dispersal — seeds ejected up to 10 feet.

Division in spring controls clump spread; remove spent capsules before they dehisce to reduce seeding.

Native region: Not native to Tennessee; ornamental introduction from Mexico and South America; listed as invasive in Florida and several Gulf Coast states.

Mexican petunia thrives in Middle Tennessee's summer heat and is nearly indestructible once established, tolerating both drought and periodic flooding. This resilience is also the plant's primary liability — it spreads by rhizome and by ejected seeds into lawn edges, mulch beds, and neighboring properties, making containment difficult in warmer microclimates of the I-65 corridor. Cultivar 'Purple Showers' is reported to set fewer viable seeds and is preferable where invasiveness is a concern. The showy purple flowers attract hummingbirds and butterflies throughout the long bloom season. In Zone 6b winters, top growth is killed by hard freezes but roots typically survive and re-sprout vigorously from the crown in May.