Plant of the Week – September 3, 2020: Mexican Petunias

This is how regular Mexican petunia looks in full bloom in September in McKinney. Pretty, but do read the details that follow.

There aren’t a lot of plants that are as showy as Mexican petunia (Ruellia brittoniana) when it’s in full bloom. It’s a strong-willed perennial that you’ll find in old landscapes all across Texas. It spreads by extremely vigorous roots that network out through beds and beyond.

Stand back, folks! This plant came to show off!

I grew up seeing it in yards that I mowed in College Station. That was a lot of years ago, and yards back then weren’t as highly manicured as what we see now. If it grew a foot or two out of bounds, no one really cared. In fact, they probably didn’t even notice. But in doing my homework for writing about it I see that my old friend has become invasive in subtropical wetlands across Southeast Texas, so it’s a definite no-go for that area.

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If you’re in a part of Texas where Mexican petunia won’t become invasive, you’ll still want to grow it 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 an edging of sorts.

Katie’s Dwarf ruellia
Bonita pink dwarf ruellia

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

Mexican petunia flower colors include blue, purple, pink and white. Individual blooms are the size of quarters. 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
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