Plant Profile: Ruellia simplex

Ruellia simplex, commonly known as Mexican petunia, is a perennial herbaceous plant belonging to the Acanthaceae family. Although it is occasionally referred to as Ruellia brittoniana, the designation R. simplex is favored since it was the original name assigned to the species when it was first documented in Cuba. This robust plant, often described as vigorous or even aggressive, features a woody base and is easily propagated through cuttings, division, or seeds. While it produces seeds abundantly, some cultivars, such as 'Purple Showers,' are sterile and may instead spread through rhizomes. In its natural habitat, Mexican petunia typically reaches heights of 3 to 4 feet, but in cultivated gardens, it usually grows to about 2 to 3 feet. The plant thrives in medium to wet, fertile, well-drained soil and prefers full sun to partial shade, with optimal flowering occurring in full sunlight. Notably, Mexican petunia is adaptable, flourishing in boggy conditions, soil that fluctuates between wet and dry, and enduring high heat and humidity. Once established, it can also withstand drought. Additionally, it is rarely affected by deer. The flowers are striking, though each bloom lasts only a single day; cutting back the stems after flowering can promote the growth of new blooms.

In garden settings, Mexican petunia can spread through rhizomes and self-seeding, having become naturalized in regions such as South Carolina, Texas, and Hawaii. Despite its impressive floral display, this species is classified as a Category One invasive species by the Florida Exotic Pest Plant Council (FEPPC) due to its tendency to invade natural habitats and outcompete native plant species in Florida.

Regarding plant health, Mexican petunia is generally free from significant insect or disease issues. However, once it establishes itself in the wild, it becomes quite challenging to remove. The plants can spread invasively through self-seeding and rhizomes, with seeds remaining viable in the soil for extended periods.