Ruellia brittoniana

This tough perennial is naturalized throughout much of the Southwest and can self-sow aggressively in the landscape. But don't be afraid to try this easy-to-grow plant with its dark-green, purple-tinged leaves and 2-inch flowers.

Flower colors include purple, blue, light pink and white. Flowers appear in mid- to late-spring and last until first frost. Leaves will turn black after a hard frost, but they will recover, said Annie McGrath, general manager at McGrath Growers in Glendale, Ariz. "It looks bad when it gets frosted, but it re-grows and looks great the following spring," she said.

It's hardy in USDA Hardiness Zones 7-10.

Contain it

In the landscape, some varieties will spread, especially in highly rich soils, said Norman Winter, horticulturist at the Central Mississippi Research & Extension Center in Raymond, Miss. But 'Katie,' a dwarf variety, will not become invasive. It might reseed, but it poses no real problem in the landscape, Winter said. 'Katie' grows 6-12 inches high.

The introduction of a dwarf Ruellia "was a great step forward" since the species can be aggressive, spreading by both seed and rhizomes, said Wayne Mackay, associate professor at the Texas Agricultural Experiment Station in Dallas.

"Katie needs no deadheading, and will continue to flower all season long, and is just as tough as its species parent, able to grow in hot, dry neglected spots," Mackay said. "In good soil, the plant will reseed true, but is not as invasive as others in the species."

Some of the low-growing varieties will grow well in a container, McGrath said. 'Katie' also can be used as a groundcover. In areas without freezes, some cultivars can grow into shrubs.

Easy to grow

Mexican petunia can be propagated by seed, vegetative cuttings or division. McGrath propagates it by cuttings.

"You can do it almost any time of the year," she said.

McGrath grows R. brittoniana plugs in 2-by-2-inch pots.

It's drought tolerant and will grow in full sun or partial shade. In the landscape it grows in a wide variety of soils from acidic to sandy to clay. McGrath doesn't use any special ingredients to grow her R. brittoniana plugs -- "just a standard mix," she said.

There are no pests or diseases associated with this plant.

Some cultivars

'Chi Chi' features narrow, dark-green leaves and 1-inch pink flowers. It grows well in moist and dry conditions. 'Colobe Pink' from Color Spot Nursery grows 8 inches tall and has pink flowers.

'Katie' is a dwarf variety with purple flowers. 'White Katie,' as the name implies, offers white flowers. 'Purple Showers' grows 4 feet tall with 2-inch, purple flowers.

{sidebar id=28}

Specifics

Name: Ruellia brittoniana

Common name: Mexican petunia, false petunia.

Description: Purple, blue, pink or white flowers appear from midspring to the first frost on serrated, purple-tinged leaves.

Propagation: Seed, cuttings or division. It self sows in the landscape.

Hardiness: USDA Hardiness Zones 7-10.

Landscape use: Perennial borders, containers or groundcover.

For more: McGrath Growers, 6208 N. 67th Ave., Glendale, AZ 85301; (888) 931-7170; http://mcgrathgrowers.com. Central Mississippi Research & Extension Center, 1320 Seven Springs Road, Raymond MS 39154; (601) 857-2284; www.msstate.edu/dept/cmrec. Texas Agricultural Experiment Station, 17360 Coit Road, Dallas, TX 75252-6599; (972) 231-5362; w-mackay@tamu.edu.

- Kelli Rodda