Carolina Wild Petunia

Carolina Wild Petunia (Ruellia caroliniensis) is found in wild woodlands from Virginia to Texas. As you might expect from a forest wildflower, this plant does best in part to full shade. Several patches grow beneath the trees in the Butterfly Garden behind the BioWorks Flight Encounter here at MOSI.

Wild petunia is very drought-tolerant. It begins flowering in spring and, under the right conditions, will continue to flower throughout the summer and fall, although not quite as robustly during the hottest summer months. It’s a small bushy plant, growing to a height of about 18 inches. A perennial in zones 6 – 10, it’s generally killed to the ground in a freeze but quickly returns. It spreads freely by seed, but small seedlings are easy to remove by hand so it’s unlikely to take over a space.

It’s a great wildflower in a wildlife garden. The pretty purple flowers are pollinated by bees and visited by butterflies, and the leaves themselves are a host plant for the Buckeye butterfly caterpillar, a common visitor to our area every spring.

Like many natives, Carolina Wild Petunia is hard to find outside of nurseries specializing in natives. Thought it grows fairly easily from seed, seeds are rarely available for purchase. If you know someone who grows this plant, you can ask if they have seeds or seedlings they’d be willing to part with.

Be careful when asking for this plant at nurseries. Another ruellia species, non-native Ruellia brittoniana, is commonly available for sale and is VERY invasive. Known as Mexican Petunia, it spreads by deep runners that are nearly impossible to get rid of. (Learn more here.) As for true petunias (Petunia x hybrida) which are available in a range of colors and sizes, they are native to South America and not closely related to our wild petunia. Though not invasive, they are generally treated as an annual in the U.S., rarely returning the following year.