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Lobelia siphilitica (great blue lobelia)
Species Distribution Map: Click to enlarge
Map Color Key © 2013 BONAP

Lobelia siphilitica

great blue lobelia

The spikes of brilliant true blue flowers on this wetland native attract butterflies, hummingbirds and neighbors to your garden! Lobelia siphilitica provides outstanding color for the border, wet meadow or pond edge. Naturalizes easily in moist soils, but tolerates periods of drought.

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2-3 Feet


12-18 Inches


12 Inches

Bloom Color


USDA Hardiness Zone 4-8

great blue lobelia Interesting Notes

This native perennial heralds the end of summer. Its showy, light to dark blue flowers, borne on a 1-3’ tall stems, are a must for the naturalized garden. Great blue lobelia flourishes in moist soil with filtered shade but will adapt to drier conditions with more shade. This herbaceous plant is easy to grow from seed and frequently self-sows. Lanceolate serrated leaves alternate along the stem, culminating into tiny bracts amidst the bell shaped blooms. Lobelia siphilitica is tolerant of acid to neutral conditions. Grow great blue lobelia with Eurybia divaricataChelone obliqua, and Eutrochium fistulosum as they enjoy the same cultural conditions and will provide varying heights in the perennial border. - Mt. Cuba Center

Great Lobelia, the blue counterpart of the Cardinal Flower, can be found in open, moist places and blooms at the same time as Cardinal Flower. The Latin species name indicates that it was once thought that Great Lobelia was a cure for syphilis. The Native Americans of this region used Lobelia as an analgesic and as a treatment for many other common ailments. - Wildflowers of Scott County

Lobelia siphilitica Growing and Maintenance Tips

Lobelia prefers moist, organically rich soil in shady to sunny areas. Tolerates drier locations than L. cardinalis, but insists on some afternoon shade in warmer zones. May self seed if happy. Infrequently, flowers are white. 

Good Substitutions

cardinal flower Lobelia cardinalis
cardinal flower Lobelia cardinalis 'Black Truffle'

Key Characteristics & Attributes

Full Sun
Full Sun
Part Sun
Part Sun
Deer Resistant
Deer Resistant
Cut Flower
Cut Flower

Additional Information

Soil Moisture Needs
Plug Type
Horticultural Plug
Landscape Plug™
Season of Interest (Flowering)
Late Summer
Green Infrastructure
Bioretention/Rain Garden
Native to North America
Propagation Type
Open pollinated