Plant of the Week – September 13, 2018: Mexican Petunia

When I stopped to take this photo of Mexican petunia in McKinney last week, the gentleman recognized me and came out to visit. “I’ve had a lot of people asking what it is,” he said. I told him I could understand why. His Mexican petunia planting has been catching my eye for many weeks, so I decided to stop.

Before I begin, an admission…
You either love this plant – or you hate it. It’s Ruellia brittoniana, Mexican petunia. It loves Texas and it shows it by spreading as vigorously as mint in our gardens. In Southeast Texas and across the Gulf Coast it has become invasive in subtropical wetlands, so be forewarned.

Continued Below


I grew up in College Station, and I knew this plant to be a willing source of unusual color (purple and blue) in the heat of the summer. It also grows in shade and part shade, an added bonus. I didn’t see it spreading invasively through neighborhoods like bamboo, although I did learn early that you don’t plant submissive little plants beside it – Mexican petunia will overtake them.

Mexican petunia grows in a garden of heirloom flowers in an older neighborhood in McKinney.

It’s best if you grow Mexican petunia in a confined space, for example, surrounded by sidewalks, driveway or patio. I’ve even considered cutting the bottom out of a 10-gallon nursery pot and sinking that flush into a bed, then planting the ruellia within it so that it could act as edging of sorts.

Katie’s dwarf ruellia

Bonita pink dwarf ruellia

Dwarf forms are also available. Katie dwarf (blue) and Bonita (pink) both grow to be 8 to 10 inches tall, and they are not nearly as assertive in their growth and spread.

Mexican petunia flower colors include blue, purple, pink and white. Individual blooms are the size of quarters and they last but one day. However, they’re produced almost continuously, so the plant is always showy.

The plants are winter-hardy from Zone 7 southward in Texas. They can be propagated from divisions, by stem cuttings or even by seed.

Posted by Neil Sperry
Back To Top