Common Name: ruellia
Type: Herbaceous perennial
Family: Acanthaceae
Native Range: Mexico
Zone: 8 to 10
Height: 0.75 to 1.00 feet
Spread: 0.75 to 1.00 feet
Bloom Time: Seasonal bloomer
Bloom Description: Violet blue
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Medium
Suggested Use: Annual, Water Plant
Flower: Showy
Leaf: Colorful, Evergreen
Culture
Winter hardy to USDA Zones 8-10. In St. Louis, grow in pots that must be overwintered indoors. Grow in organically rich, medium to wet soils in full sun to part shade. Best in filtered sun or morning sun with some part afternoon shade and with high humidity. Seed may be started indoors in small pots 6-8 weeks before last frost date. Place pots outside in mid May. Soils must be kept consistently moist. Pots may be sunk into mud at the edge of water gardens with up to 2-3” of water covering the plant crowns. Cut back foliage in fall before first frost and bring pots indoors for overwintering. Keep soils of overwintered plants only slightly moist. Stem cuttings may be taken in spring for new plants.
Noteworthy Characteristics
Ruellia squarrosa is native to tropical South America. It is a frost tender perennial that is often grown as an aquatic in water gardens or small ponds. It typically grows to 10-12” tall with a similar spread, and features petunia-shaped violet blue flowers with ruffled dark purplish-green leaves. Blooms in summer. Most botanical authorities, including Hortus Third and RHS, do not recognize R. squarrosa as a botanical species, but consider it to be descriptive of an unidentified form.
Genus name honors Jean de la Ruelle (1474-1537), French herbalist and physician to Francois I (1494-1547) who was king of France from 1515 until his death in 1547.
Problems
No serious insect or disease problems.
Uses
Sink pots to the rim at the edge of ponds or water gardens. Pots may also be placed in other mostly sunny locations around the home. In semi-tropical areas, this plant is sometimes grown year round as a ground cover.