Did you know that America has it’s own native petunias? Well now you do. Commonly referred to as Wild Petunia, there are multiple species that bloom light purple to lavender flowers from May until Frost native throughout North America. They are great at attracting a variety of bees to one’s yard.
In this article I’m going to describe the most common types of Wild Petunia, what they look like, where you can grow them, and what wildlife they will attract. At the end, you should have a good idea what species would be best for you in your gardening situation, and how to get them.
In this article:
- What is Wild Petunia
- What are the benefits of Wild Petunia
- Identification / Characteristics
- How to grow and care for Wild Petunia
- What Wildlife, Pests, and Diseases effect Wild Petunia
- Where to buy Wild Petunia
- Uses of Wild Petunia
- Final thoughts
What is Wild Petunia
Wild Petunia is a common flower name that is applied to several species of the Ruellia genus that are native the North America. And while there are 17 native species of the Ruellia genus, four of those are commonly referred to as Wild Petunia:
- Carolina Wild Petunia, Ruellia carolineinsis, grows in moist-to-dry woodlands in partial shade, but can also find itself growing in a yard (self-seeding). It grows 2-3′ tall and blooms from late Spring until Fall, and is native to the Southeastern United States. 
- Hairy Wild Petunia, Ruellia humilis, grows in open meadows, roadsides, yards, and disturbed areas in full sun and well-draining soil. Only growing 6-12″ tall, it makes an attractive groundcover and self-seeds readily. It is primarily native to the middle United States from the Great Lakes to Texas. 
- Stalked Wild Petunia, Ruellia pedunculata, grows up to 2′ tall and is found isolated in full or partial sun in medium-moist to dry forests, cliffs, cedar glades, streambanks, or along railroad tracks/roads. Overall very similar to R. strepens, but has much longer flower stems (penduncles). 
- Smooth Wild Petunia, Ruellia strepens, grows in light shade or partial sun in moist rocky or loamy soil in woodlands or thickets. Growing 1.5′-3′ tall, it is shorter lived than other members of the genus, lasting for only 2-3 years. Like other members, it will self-seed. The stems and foliage are more smooth and often hairless.
- (click on image to enlarge)
- Native Range of Smooth Wild Petunia (click to enlarge)
Although each of these species of Wild Petunia inhabit different ranges and can have very different growing conditions, they all look fairly similar. All have funnel shaped lavender to purple flowers, all have opposite leaves that can take on a lanceolate shape, all can self-seed depending on the number of flowers they produce. The primary differences are in the height and habitat.
Hairy Wild Petunia is a shorter species (6-12″ tall) that does well in full sun, and nearly any kind of soil. While the other Wild Petunia species listed all grow anywhere from 2 to 3′ tall and prefer a shadier habitat.
Native Range of Wild Petunia
The overall range of Wild Petunia in the United States is large. Large (or entire) areas of Texas to Florida, then North to Iowa and Pennsylvania are home to various species of the Ruellia genus.
Wild Petunia Reference Table
|Scientific Name||Ruellia caroliniensis, Ruellia humilis, Ruellia strepens, Ruellia pedunculata|
|Common Name(s)||Wild Petunia, Carolina Wild Petunia, Hairy Wild Petunia, Prairie Petunia, Fringeleaf Wild Petunia|
|Native Range, USDA Zone||Central North America, USDA Hardiness zones 4-8|
|Bloom Duration, Color||4 Months, purple to lavender|
|Height||6-12″ (15-30 cm)|
|Spacing / Spread||12-18″ (30-45 cm)|
|Light Requirements||Full sun|
|Soil Types||Sandy to clay, must drain well!|
|Moisture||Moist to dry|
|Fauna Associations / Larval Hosts||Bees|
What are the Benefits of Wild Petunia
Wild Petunias are beautiful flowers. The funnel shaped purple-lavender blooms look attractive in nearly any setting.
There is such a wide variety of species that there is a Wild Petunia that can grow in most any conditions. With ranges covering the Southwest United States to the cold wet North East, there is a Wild Petunia for almost any environment or climate.
Long Bloom Time
Just about all Wild Petunias bloom for at least two months, making them one of the longest-blooming perennials native to the United States.
Identification and Characteristics of Wild Petunia
Wild Petunia will generally always have a round, light green stalk. Different species will have different heights though, as well as some are quite hairy while others are smooth.
Wild Petunia will have a funnel-shaped purple to lavender flower that occurs at the leaf axils or at the end of a stalk. Flowers are about 2″ wide and long.
In addition to the beautiful lavender flowers, Wild Petunia will also produce cleistogamous flowers. These are small closed flowers that never open, and will self-pollinate eventually producing seed. Cleistogamous flowers begin producing in mid-Summer, but will often continue until late Summer/Fall. 
Wild Petunia has fibrous root system.
Quick ID Reference Guide to different species of Wild Petunia (Ruellia)
Below I try to summarize the botanical differences of the four main Wild Petunia species. Since they often have overlapping native ranges, it can be quite helpful to be able to learn these characteristics in order to determine which species you are looking at.
|Species||Common Name||Stalk / Stem||Leaves||Flowers||Soil||Moisture|
|Ruellia caroliniensis||Carolina Wild Petunia||Erect, smooth to hairy, 2′ tall (60 cm)||Opposite, simple, ovate to lanceolate shaped (4″ long by 2″ wide)||2 or more flowers clustered in leaf axils, and short lobed (1/2″)||Rocky to loamy soil, well drained||Dry to medium|
|Ruellia humilis||Hairy Wild Petunia||6-12″ tall, branching, hairy.||Opposite leaves, lanceolate to ovate, 1-2.5″ long by 1″ wide, hairy, smooth margins.||Multiple solitary flowers that bloom for one day.||Sandy, rocky, loamy, clay-loam. Well-drained.||Dry to moist. Well drained.|
|Ruellia strepens||Smooth Wild Petunia||Erect, branching, up to 3′ tall. Slightly hairy or smooth.||Opposite leaves 5″ long x 3″ wide, ovate to lanceolate with smooth or slightly serrated margins.||1-3 flowers emerge from axils of the mid-to-upper leaves with short||Rocky to loamy soil, well drained.||Medium to moist soil.|
|Ruellia pedunculata||Stalked Wild Petunia||Erect, branched, slightly hairy, up to 2′ tall (60 cm)||Opposite, simple lanceolate (4″ long), smooth margins, slightly hairy||1-3 solitary flowers per plant||Rocky to loamy soil, well drained||Dry to medium|
How to Grow Wild Petunia from Seed
One thing most species of Wild Petunia share is how to germinate the seeds. In general, Wild Petunia seeds need around 60 days of cold moist stratification to germinate. The planting depth is shallow, with just a light dusting of soil. 
The best way to achieve the cold stratification and break the seeds dormancy is to either Winter Sow the seed or simulate winter in the refrigerator.
But if you are winter sowing, or have stratified your seed, you simple fill a suitable container with moist potting soil. Press the seeds into the soil, and place the container in a location that receives morning sun and afternoon shade. Keep the seeds moist, and you should expect germination within 2-3 weeks.
Wildlife, Pests, and Diseases associated with Wild Petunia
Wild Petunia is popular with bees, butterflies, and some other insects that feed destructively on the foliage or bore into the stems. It mostly attracts long-tongued bees as it is difficult to reach the nectar down the throat of the flower. 
There are several different species that feed destructively on the foliage, but they don’t do enough damage to harm the appearance of the plant.
Deer and Rabbits
Wild Petunia will be browsed by deer and possibly rabbits. Excessive deer pressure has been noted as being a possible reason for local populations going extinct.
Wild Petunia is not effected by diseases. It doesn’t seem to ever be effected by foliar disease of any kind.
Where you can buy Wild Petunia
Wild Petunia is not typically sold in nurseries, as it isn’t a typical ‘garden friendly’ plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map.
Where to buy seeds
We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.)
Uses of Wild Petunia
The appropriate garden use of Wild Petunia will depend on you matching the appropriate species to it’s growing conditions. As previously noted, many species thrive in partial shade, while Hairy Wild Petunia will thrive in full sun.
Nonetheless, most Wild Petunia species will be well-behaved, while Hairy Wild Petunia will self-seed aggressively.
I’ve not found any documented medcinal uses of the Native Wild Petunias. Although there were old reports from the 1800’s of them having medicinal properties. Nonetheless, research is on-going with some of the species to determine if they can offer any value to humanity as a medicine. 
Wild Petunia is a beautiful small flower showing lovely lavender colored blooms for long stretches during the Summer. Although there are many different species, they all have a similar appearance and primarily differ by height and growing conditions. As natives, they do host some insects and for that reason alone should be considered as superior to the all-too-common exotic petunias that seem to decorate every corporate or business flower bed.
 – USDA NRCS – Ruellia humilis. Accessed 19DEC2022
 – Mohlenbrock, Robert H. Wildflowers : a quick identification guide to the wildflowers of North America, New York : Macmillan ; London : Collier Macmillan, 1987, pp.203. Accessed 19DEC2022.
 – Holm, Heather. Pollinators of native plants: attract, observe and identify pollinators and beneficial insects with native plants. No. 595.79 H747p. Pollination Press, 2014.
 – Long, Robert W., and Leonard J. Uttal. “SOME OBSERVATIONS ON FLOWERING IN RUELLIA (ACANTHACEAE).” Rhodora, vol. 64, no. 759, 1962, pp. 200–06. JSTOR, http://www.jstor.org/stable/23306493. Accessed 22 Dec. 2022.
 – Tripp, Erin A. “The Current Status of Two Rare Species of Ruellia (Acanthaceae) in Pennsylvania.” Bartonia, no. 62, 2004, pp. 55–62. JSTOR, http://www.jstor.org/stable/41610107. Accessed 21 Dec. 2022.
 – Clark, Julia, and Janette Steets. “The role of predispersal seed predators and their parasitoids for Ruellia humilis reproduction.” Research Reports from Life Science Freshmen Research Scholars 2.1 (2016). Archived 21DEC2022.
 – Baskin, Jerry M., and Carol C. Baskin. “Temperature relations of seed germination in Ruellia humilis, and ecological implications.” Castanea (1982): 119-131. Accessed 22DEC2022
 – Robertson, Charles. “Flowers and insects; lists of visitors of four hundred and fifty-three flowers.” (1928).
 – Rathcke, Beverly J. “Insect-Plant Patterns and Relationships in the Stem-Boring Guild.” The American Midland Naturalist, vol. 96, no. 1, 1976, pp. 98–117. JSTOR, https://doi.org/10.2307/2424571. Accessed 21 Dec. 2022.
 – Nirmaladevi, R., and P. R. Padma. “A study on the antioxidant potential of three under-exploited plants of medicinal value.” Plant Archives 8.1 (2008): 339-341.
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