While filling my watering can from the rain barrel this afternoon, I stopped to admire the Mexican Petunias thriving along the fence (well, my neighbor's fence, but my petunias). Their happy purple blooms were drawing bees in the late afternoon sun, and they danced in the breeze blowing from the lake. What a great flower for Florida - hardy, drought-tolerant, easy to care for - everyone should have these in their (screech! "Hey, what's going on? Give back my microphone! This is my blog! What are you doing?" screech!)
LADIES AND GENTLEMEN, THIS INTERRUPTION IS BROUGHT TO YOU BY THE EMERGENCY BROADCASTING SYSTEM...OF INVASIVE PLANTS. WE ARE HERE TO TELL YOU THAT MEXICAN PETUNIA IS HIGHLY INVASIVE AND IS LISTED AS A CATEGORY 1 INVASIVE SPECIES BY THE FLORIDA EXOTIC PEST PLANT COUNCIL. DO NOT LISTEN TO ANYTHING THIS PERSON IS TELLING YOU. MEXICAN PETUNIA IS INVASIVE AND MUST BE AVOIDED IN FLORIDA-FRIENDLY GARDENS. THAT IS ALL.
Geez, guys, you didn't give me a chance to finish! You're absolutely right. Mexican Petunia (Ruellia brittoniana) is absolutely an invasive species in Florida. Even though you find it at nearly every nursery, especially the big box stores, Mexican Petunia is actually a terrible plant for a Florida-Friendly yard.
What is an invasive species, anyway? Simply put, an invasive species is one that is not native to the area, but thrives here to the detriment of local species. Some non-native plants are fine, because they're easy to control or don't complete with local species. But an invasive plant is a real problem, because it takes over the environment, with little or no help from humans, and spreads like crazy. If you want to learn more, click on over to the Florida Invasive Plant Education site.
So why the heck would I have terribly invasive non-native Mexican Petunias in My Florida Backyard? Here's why: I use a sterile cultivar of this plant. This means that the plant has been cultivated so that it can't propagate on its own. The MPs I plant in my yard will stay only in my yard, and will not spread out of control. The only place I've been able to find this sterile cultivar Mexian Petunia (believe it or not!) is at my local Home Depot nursery. They sell plants from Riverview Flower Farm (the ones that come in the green pots).
Here's the deal: If you have Mexican Petunia in your yard, and you don't know whether it's sterile or not, then it's probably not. I highly recommend you pull it out, all of it, and replace it with something more Florida-Friendly. You could try the Wild Petunia, which is similar, but I have to admit I didn't have much luck with it. Or look for something completely different - remember to try the Florida Friendly Plant Database.
Or, if you want, try the sterile cultivar. I've had luck with it, and after a year, it has not spread beyond where I've planted it. It does get a little...broad - in order to keep it from drooping out onto the path, I tie it up to bamboo stakes. I think it makes a responsible addition to My Florida Backyard, and I'm glad we have it.