Lobelia 'Grape Knee-Hi'

Common Name: lobelia 
Type: Herbaceous perennial
Family: Campanulaceae
Zone: 6 to 9
Height: 1.50 to 2.00 feet
Spread: 1.00 to 1.50 feet
Bloom Time: July to September
Bloom Description: Deep purple
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Medium
Suggested Use: Rain Garden
Flower: Showy
Tolerate: Deer, Wet Soil


Grow in rich, medium to wet soils in full sun to part shade. Needs constant moisture. Tolerates full sun in northern climates, but appreciates part afternoon shade in hot summer climates of the lower Midwest and South. In nature, lobelias are typically found in wet areas such as bogs, moist meadows and along streams. Divide clumps in spring. Root mulch should be applied in cold winter climates such as St. Louis to protect the root system and to prevent root heaving.

Noteworthy Characteristics

Lobelia is a genus of about 370 species of annuals, perennials, shrubs and some aquatics. They grow in tropical and temperate areas worldwide but many come from North, Central and South America.

Genus name honors Matthias de l'Obel (1538-1616), French physician and botanist, who with Pierre Pena wrote Stirpium Adversaria Nova (1570) which detailed a new plant classification system based upon leaves.

'Grape Knee-Hi' was bred by Terra Nova Nurseries of Canby, Oregon and originated as a cross between a dwarf, unpatented Lobelia siphilitica as the seed parent and an unnamed and unpatented Lobelia interspecific hybrid as the pollen parent. It is a dwarf cardinal flower with an upright well-branched habit and a basal rosette of dark green toothed leaves. Its tubular, two-lipped, sterile flowers are grape-purple and will bloom from mid summer to fall. 'Grape Knee-Hi' grows 1 1/2 to 2 ft. tall and 1 to 1 1/2 ft. wide. It was a Top Performing Perennial at the Massachusetts Horticultural Society field trials in 2015. United States Plant Patent PP#13,264 issued November 19, 2002.


No serious insect or disease problems. Snails and slugs may damage the foliage.


Effective in moist areas of woodland/shade gardens, wet meadows or along streams or ponds. Also adds late summer bloom and height to borders as long as soils are kept uniformly moist.