Native Plant: Wild petunia

NATIVE PLANT

Editor's note: Once a month, the OSU Extension master gardener's office of Franklin County profiles a plant that occurs naturally in central Ohio.

Seeking a perennial replacement for annual petunias? The wild petunia (Ruellia humilis) might be just what you are desiring.

With a growth pattern that is mostly upright to somewhat sprawling, the wild petunia isn’t particular wild-looking, nor is it part of the petunia family. This lovely plant, which is native to most of the eastern United States, is a member of the Acanthaceae family. Its tubular, bell-shaped, lavender-to-lilac-colored flowers do mimic petunias — with the added benefit that the blooms self-deadhead each day.

Each morning the blooms, which measure between 1½ to 2½ inches across, open up. And each evening they fall off. 

Another feature of this herbaceous perennial is that it blooms during the hottest summer months — July to October — just as many other perennials are beginning to fade away. The fringed leaves are light- to medium-green and are covered with soft white hairs, leading to other common names such as fringeleaf petunia and hairy petunia.

The wild petunia usually grows to a foot in height, though it can get as tall as 2 feet. It is often used in borders, native plant gardens, rock gardens, wild gardens or prairies. It is a hardy plant, with seeds that can explode outward up to 10 feet.

Although not typically available in conventional nurseries or gardens, the wild petunia is becoming more popular in native plantings, such as those found at the Ohio Governor's Residence and Heritage Garden and at native plant sales around Ohio. 

When in bloom, it attracts a number of pollinator insects. The purple lines that radiate from the center of the petals serve as a visual guide to nectar, rather like a lighted landing strip. The wild petunia is particularly attractive to long-tongued bees and butterflies, and is a host plant for common Buckeye butterfly larvae.

Growing requirements

Hardiness zones: 3-9

Sun: partial shade

Water: low

Soil: moist

Propagation: Stem cuttings taken in June or July and treated with hormone give the best results for propagating. Cuttings can be held in a cold frame until spring. Although it produces an abundance of seeds, germination is low.

Pests and diseases: No serious pest or disease problems.