Silent Invader: Mexican Petunia, Ruellia simplex

Love and Hate
A landscaped bed of the sterile cultivar of Purple Showers adds some landscape color. Photo by Ann Murray
A landscaped bed of the sterile cultivar of Purple Showers adds some landscape color. Photo by Ann Murray, 2002 University of Florida

Facebook gardening groups will light up at the mention of Mexican Petunia, Ruellia simplex. Comments like “Worst weed ever!”, “My favorite plant!”, “Invasive! Pull it out quickly!”, and “It’s so easy to grow, I love it”. Once again the battle begins on another of Florida’s Silent invaders. Unlike Lantana, which sneakily pops up; thanks to transportation by hungry birds, Ruellia, as we will call it for the rest of this article, is more in your face. Not long after the first bloom, you can expect most varieties to seed and pop up all over your garden. Any crevice, from a crease in your wood garden box to a crack in your driveway is a possible growing spot for this prolific plant.

Opinions or Fact

There will be those gardeners that swear they have grown it for years and it has never reared its pretty face. Others will swear it as a scourge that has invaded every corner of their yard. Either case could be true depending on which cultivar you have. A long time cultivar called Purple Showers does not spread from seed but can spread underground by rhizomes. It can sometimes be found at garden centers but there is a potential for mislabeling. You will know within a few months of planting it if seedlings do not show up. We have been growing it at the Extension office butterfly garden for years without a single seed sprouting. We sell it every year at our November Garden Festival and Plant sale.

A tray of recently rooted Purple shower cuttings.
A tray of recently rooted Purple Showers will soon be planted and grown out for the Highlands County Master Gardeners Garden Festival and Plant Sale. Purple Showers is sterile and can only be grown from cuttings. Photo by David Austin
Making Better Choices

The University of Florida, which studies invasive potential of introduced plants has deemed Ruellia simplex a Category 1 invasive. On a scale from 1 to 2, unlike hurricanes, 1 is considered more invasive. You can read their assessment here. Along with assessing the plant they have done something just as helpful. They have bred a cultivar series that is sterile. The ‘Mayan’ Series flowers come in purple, pink, and white as taller versions and a dwarf purple. The three tall varieties all have plant patents and the dwarfs patent is pending. Buying any of the ‘Mayan’ Series assures you will be getting them as labeled.

Responsible Gardening

Sterile varieties of Ruellia simplex are hardy and colorful plants and attractive to pollinators. As a responsible gardeners, we only hope that you foster and promote the sterile varieties. That’s what’s new from the Hometown Gardener. Like and Follow me on Facebook at Hometown Gardener.

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david austin
Posted: June 18, 2019

Category: Agriculture, Florida-Friendly Landscaping, Horticulture, Invasive Species, Pests & Disease, UF/IFAS Extension
Tags: Conservation, Gardening, Highlands County, Highlands Horticulture Digest, Hometown Gardener, Invasive Species, Pollinator Plants, Weeds

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