Ruellia simplex, the Mexican petunia, Mexican bluebell or Britton’s wild petunia, is a species of flowering plant in the family Acanthaceae that is native to Mexico, the Caribbean, and South America. It has become a widespread invasive plant in Florida, where it was likely introduced as an ornamental before 1933, as well as in the eastern Mediterranean, South Asia and other parts of the eastern hemisphere.
This is a cold-hardy plant that grows well in U.S. Department of Agriculture zones 7 through 11. In cooler areas, it can be grown as an annual. In warmer climates, it has a long bloom season and requires little maintenance to not only produce flowers but to thrive and spread as a lovely ground cover. Its drought resistance and ability to grow well in difficult climates and nutrient-deficient soils make it a favorite for those looking to include low-maintenance plants in their outdoor landscapes.
The Mexican petunia grows best in warmer climates and is prolific in its reach. It is native to South America and Mexico. It has naturalized in South Carolina and Texas as well as the far reaches of the island of Hawaii. In Florida, the flowering plant is considered an invasive species that crowds out plants that are native to the state.
Characteristics
- Appearance: Mexican Petunia is an evergreen, herbaceous perennial that can grow up to 3-4 feet tall in the wild, but typically reaches 2-3 feet in gardens. It has dark green, lance-shaped leaves that can be tinged with purple and produces trumpet-shaped flowers in shades of purple, pink, or white.
- Flowering: The flowers are papery and trumpet-shaped, resembling petunias, and bloom from late spring through fall. Each flower lasts only a day, but the plant continuously produces new blooms, creating a long-lasting display.
- Invasiveness: Mexican Petunia is known for its vigorous growth and can spread quickly by rhizomes and self-seeding. It is considered invasive in some regions, such as Florida, where it can displace native plants.
- Attractiveness to Wildlife: The plant attracts butterflies, including swallowtails, brush-footed butterflies, and monarchs, who enjoy the nectar from its flowers.
Cultivation
- Soil: Prefers medium to wet, fertile, well-drained soil. It can tolerate a range of soil conditions, from boggy wet areas to drier sites once established.
- Light: Thrives in full sun to partial shade. In full sun, the stems may turn more purple, while in shade, they remain green2.
- Watering: Requires regular watering, especially during the first growing season to establish a deep root system. Once established, it is drought-tolerant.
- Propagation: Easily propagated by seeds, stem cuttings, or division. Seeds can be harvested from the pods before they burst open and sown in pots or garden beds.
- Maintenance: Cut back stems after flowering to encourage new blooms. It may need staking to prevent the tall stems from flopping.
- Pests and Diseases: Virtually pest and disease-free