Flower description and bloom time
This prairie native has light lavender petunia-like flowers that are 1 ½ inches in diameter. Wild petunia blooms sporadically from June through October; flowers usually fall off cleanly so deadheading is unnecessary.
Foliage interest—color / texture
Wild petunia’s fuzzy green foliage remains ornamental throughout the entire season.
Habit and growth rate observations
The low sprawling growth habit, 6 to 8 inches tall, will trail across or climb up and over depending on the neighboring plants.
Site preference—soil and light
The wild petunia enjoys full sun and moderate soil types; however, it will tolerate dry soils after becoming established.
Successes and possible drawbacks—how to overcome them
The trailing habit and tendency to self-seed can be a deterrent for some gardeners. When planted in adverse conditions like outcropping in a rock garden, the trailing habit can be a used to soften the edges. Also works well as a groundcover or in combination with other aggressive perennials.
Notes from growers / retailers
Ruellia is slow growing and unattractive in the container in spring. By midsummer the plant is fuller but still somewhat leggy. Best results in containers are achieved if the plants are kept on the drier side. Wild petunia is pest-free in containers and in the garden.
Wild petunia is best planted with drought tolerant plants such as prairie dropseed [Sporobolus], sedum, and daylilies.
Parting SHOT” —the overall evaluation results were Fair **
Due to its tendency to self-seed everywhere, it was given a rating of Fair in the overall appearance category. Not a good plant for the typical backyard garden, but a good pick for a tough site; e.g. a parking median bed. While limited in its applications, Ruellia humilis does fill a need in some gardens. Its trailing habit, drought tolerance and soft violet, long-blooming flowers make it appropriate for the rock garden or the drought-resistant prairie. Its lengthy bloom time will add color to your garden for much of the summer into fall!