great blue lobelia

Lobelia siphilitica


Sometimes called blue cardinal flower, great blue lobelia likes full sun but will tolerate partial shade. Plants grow from 1′-4′ tall. Blooms with multiples flowers on a single stalk from mid summer through fall. It wants medium to moist soil and does not tolerate drought. Often found in ditches or on wetland fens. Once established lobelia can form large patches. Each plant is a short lived perennial (with each plant living for only a few years).


Great lobelia likes rich moist soils with plenty of humus. Plants can be divided in the early spring. Plants will grow from seed if given good growing conditions.


All parts are poisonous. Toxic only if eaten in large quantities. Symptoms include nausea, vomiting, diarrhea, salivation, exhaustion and weakness, dilation of pupils, convulsions, and coma. Toxic Principle: Alkaloids lobelamine, lobeline, and others, plus a volatile oil. (Poisonous Plants of N.C.)


great blue lobelia

Sample Description
USDA Symbol: Common Name: Scientific Name:
LOSI great blue lobelia Lobelia siphilitica

ITIS TSN: 34531

Category: Dicot


Kingdom: Plantae


Super Division: Spermatophyta

Division: Magnoliophyta


Class: Magnoliopsida

SubClass: Asteridae

Order: Campanulales

Family: Campanulaceae

Counties: Barron, Brown, Buffalo, Burnett, Calumet, Clark, Columbia, Crawford, Dane, Dodge, Door, Dunn, Eau Claire, Fond du Lac, Grant, Green, Green Lake, Iowa, Iron, Jackson, Jefferson, Juneau, Kenosha, Kewaunee, La Crosse, Lafayette, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Marquette, Menominee, Milwaukee, Monroe, Oconto, Outagamie, Ozaukee, Pepin, Pierce, Polk, portageprice, Racine, Richland, Rock, Rusk, Sauk, Sawyer, Shawano, Sheboygan, St. Croix, Taylor, Vernon, Walworth, Washburn, Washington, Waukesha, Waupaca, Waushara, Winnebago, Wood

Natural Community: Calcareous Fen

Coefficient of Conservation: 5

Duration: Growth Habit: Native Status:
Perennial Forb/herb L48(N)CAN(N)

Active Growth Period: spring-summer-fall

After Harvest Regrowth Rate:


Carbon to Nitrogen Ratio:

Coppice Potential:

Conspicuous Fall Color: Yes

Fire Resistant: No

Flower Color:

Conspicuous Flower: Yes

Foliage Color: Green

Foliage Light Porosity Summer:

Foliage Porosity Winter:

Foliage Texture:

Fruit/Seed Color: Black

Fruit/Seed Conspicuous: No

Growth Form: Single Stem

Growth Rate:

Height at Base Age (Max):

Height at Maturity:

Known Alelopath: No

Leaf Retention: No


Low Growing Grass: No


Shape and Orientation: Erect

Toxicity: Moderate

Height (min): 12

Height (max): 48

Root Type: Fibrous

Adapted to Coarse Textured Soils:

Adapted to Medium Textured Soils:

Adapted to Fine Textured Soils:

Anaerobic Tolerance:

CaCO3 Tolerance:

Cold Stratification Required:

Drought Tolerance: Low

Fertility Requirement:

_Fire Tolerance:

Frost Free Days, Minimum:

Hedge Tolerance: None

Moisture Use: Medium, High

pH (Minimum):

pH (Maximum):

Planting Density per Acre, Minimum:

Planting Density per Acre, Maximum:

Precipitation (Minimum):

Precipitation (Maximum):

Root Depth, Minimum (inches):

Salinity Tolerance:

Shade Tolerance: Partial

Temperature, Minimum (°F):

Plant Spacing (min): 12

Plant Spacing (max): 12

Bloom Period: Commercial Availability: Fruit/Seed Abundance:
Summer Routinely Available Medium
Fruit/Seed Period Begin: Fruit/Seed Period End: Fruit/Seed Persistence:
Summer Fall Yes
Propogated by Bare Root: Propogated by Bulbs: Propogated by Container:
No No Yes
Propogated by Corms: Propogated by Cuttings: Propogated by Seed:
No No Yes
Propogated by Sod: Propogated by Sprigs: Propogated by Tubers:
No No No
Seeds per Pound: Seed Spread Rate: Seedling Vigor:
7520000 Moderate
Small Grain: Vegetative Spread Rate: Propagation Treatment:
No Moist Stratification
Days to Stratify: Direct Sowing Time:
30 early-springspring

Benefits: Birds, Butterflies, Deer Resistant, Host Plant, Hummingbirds, Pollinators

Berry/Nut/Seed Product: Christmas Tree Product: Fodder Product:
No No No
Fuelwood Product: Lumber Product: Naval Store Product:
-- No No
Nursery Stock Product: Palatable Browse Animal: Palatable Graze Animal:
No -- --
Palatable Human: Post Product: Protein Potential:
No No --
Pulpwood Product: Veneer Product:
No No


WisFlora Database detailed list of herbarium samples collected across Wisconsin including the location of each.


USDA Plants Database
Wisconsin Virtual Flora Database 
Lady Bird Johnson Wildflower Center