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Garden Club of Cape Coral | Wild petunias

By ANN BLOCK - Garden Club of Cape Coral | Mar 29, 2024

The wild petunia plant. PROVIDED

Excited about the warmer March weather, I recently went to the All Native Nursery in Fort Myers looking for flowers to enhance my spring garden. I wanted flowers to attract birds, bees and butterflies.

I have seen many purple Mexican petunias in our neighborhood. I knew they are invasive but wanted something similar. At the nursery, I found purple wild petunias (Ruellia caroliniensis) and decided to choose three pretty lavender flowering plants. When I got home, I researched this flowering plant. To my delight, this is what I found online and I’d like to share with all my fellow gardeners.

The wild petunia is a pretty little plant native to much of the eastern U.S. and Florida. This lovely plant isn’t actually a petunia (which are relatives of the tomato) but rather a member of the Acanthaceae family. Either way, the resemblance is striking. 

Standing about a foot in height, wild petunia is an excellent addition to a bed with other short plants. In ideal conditions, this plant can exceed one foot and spread quite vigorously. In Florida it is blooming throughout the hottest, driest times of the summer. While other plants are withering away, wild petunia will be going strong. It is quite a hardy species as well, handling most conditions, except for shade and wet swampy soil. In fact, it’s so hardy that it can be a bit aggressive, so keep an eye on where seedlings turn up. It does great as a ground cover, with a sidewalk or something to contain it. When mature, the seeds literally explode from the plant, traveling upwards of 10 feet! 

When in flower, wild petunia attracts a wide variety of insect pollinators, but the lavender blooms are especially attractive to long tongued bees and butterflies. To my delight, I found that it is also a host plant for the common buckeye and white peacock butterflies. Other common names for Ruellia humilis include prairie petunia, fringeleaf wild petunia, and hairy Ruellia.

It is an herbaceous, long-lived perennial and one of the first wild flowers to bloom in the spring. It has a strong woody root system that allows it to survive our cool Florida weather and quickly come back in the spring. It also holds up very well for transplanting.

Carolina wild petunia is a must-have plant for pollinator gardens. It is a source of nectar and pollen for bees, butterflies, wasps and hummingbirds. 

It self-seeds readily. Seeds can also be harvested once the flower withers and the seed capsule turns brown. Seeds should be cold stratified to insure germination. It can also be propagated from cuttings and plant divisions after a few years.

If you find it growing in your lawn, consider transplanting it to a garden where you can enjoy its beauty and it can benefit the pollinators. It can handle full sun to part shade. It likes sandy, well-drained alkaline soil. It has good drought tolerance. It will grow to a height of 12 to 24 inches.

Although plants in the Ruellia genus may be called “petunias” they are not even closely related to true petunias, which are members of the Petunia genus. It is only the similarity in appearance that give them their common name.

Please be aware that many big box stores and nurseries sell the non-native Mexican petunia (Ruellia simplex) which should be avoided because it spreads via underground rhizomes, does not respond well to herbicides and has been classified a Category I invasive species that is displacing native species. For more information, contact University of Florida on Mexican petunias.

I encourage you to look for Florida friendly flowers, plants and trees. Have fun with your Spring Garden.

I’d like to leave you with a quote from the famous artist, Monet…

“I must have flowers’ always, always, always.”

Happy gardening!

Ann Block is Past President of the Garden Club of Cape Coral.