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PlantFiles: Great Blue Lobelia
Lobelia siphilitica

Family: Campanulaceae (kam-pan-yew-LAY-see-ee) (Info)
Genus: Lobelia (low-BEE-lee-a) (Info)
Species: siphilitica (sigh-fy-LY-tih-kuh) (Info)

17 vendors have this plant for sale.

61 members have or want this plant for trade.

View this plant in a garden


24-36 in. (60-90 cm)

18-24 in. (45-60 cm)

USDA Zone 4a: to -34.4 C (-30 F)
USDA Zone 4b: to -31.6 C (-25 F)
USDA Zone 5a: to -28.8 C (-20 F)
USDA Zone 5b: to -26.1 C (-15 F)
USDA Zone 6a: to -23.3 C (-10 F)
USDA Zone 6b: to -20.5 C (-5 F)
USDA Zone 7a: to -17.7 C (0 F)
USDA Zone 7b: to -14.9 C (5 F)
USDA Zone 8a: to -12.2 C (10 F)
USDA Zone 8b: to -9.4 C (15 F)
USDA Zone 9a: to -6.6 C (20 F)
USDA Zone 9b: to -3.8 C (25 F)

Sun Exposure:
Sun to Partial Shade
Light Shade

All parts of plant are poisonous if ingested

Bloom Color:
Medium Blue

Bloom Time:
Mid Summer
Late Summer/Early Fall


Other details:
Requires consistently moist soil; do not let dry out between waterings
Very high moisture needs; suitable for bogs and water gardens

Soil pH requirements:
6.1 to 6.5 (mildly acidic)
6.6 to 7.5 (neutral)

Patent Information:

Propagation Methods:
By dividing the rootball
From seed; stratify if sowing indoors
From seed; sow indoors before last frost

Seed Collecting:
Allow pods to dry on plant; break open to collect seeds
Properly cleaned, seed can be successfully stored

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15 positives
3 neutrals
No negatives

Gardeners' Notes:

Neutral kydrummer On Jun 22, 2014, kydrummer from Silver Spring, MD wrote:

Bought this for use at a farm because it had a tag in the pot "Deer won't eat this!". Deer in Maryland chop it down to stumps.

Positive wakingdream On Aug 8, 2013, wakingdream from Allentown, PA wrote:

Having grown this native plant by using one small seedpod found in a creek setting, I later returned to disperse more seeds to make up for my removal. I grew dozens easily in winter sowing jugs. The small Lobelia seedlings were robust enough to survive the separation after being tugged apart from the large clump inside the jug. They were eventually positioned on the shady, moist north side of my home, a match for the conditions in which I found the original plant. The shade of blue is captivating. Bloom time is August and September here in southeast PA. I noticed a vast number of seedlings appearing earlier this summer and will pot them up for gardening friends.

Positive plant_it On Jun 18, 2013, plant_it from Valparaiso, IN wrote:

I can't wait to have the problem of too many seedlings b/c it spreads aggressively. Just getting to know this plant but its quickly becoming one of my favorites.

Positive tauberp On Jan 4, 2012, tauberp from Aurora, IL wrote:

My favorite flower! Beautiful and very long blooming, with long flowering stalks. We have those in our front yard in front of yews and boxwoods and get a lot of compliments for those. Easy to grow and low maintenance, with mid summer to fall blooming period. Heavy clay soil and get not much water there, and it's north side with part shade, but doesn't stop it from thriving. We also have on the side of the house where it gets morning sun, and it is the most outstanding flowering plant we have. I love those deep blue flowers!

Neutral EllaTiarella On May 31, 2010, EllaTiarella from Portage, MI (Zone 5b) wrote:

It's invasive in my garden; however, I do appreciate the late-season color. I bought one plant two years ago, it got ahead of me, and now it's "everywhere"! I think I have over 50 plants here and there in the 20 feet or so around the original. I plan to dig quite a bit of it out, and leave just a clump or two. My recommendation is to be on guard for seedlings, and be sure to dig them out right away where they are not wanted. Perhaps prompt deadheading would help.

Positive jmorth On Dec 3, 2009, jmorth from Divernon, IL (Zone 5b) wrote:

Blooms late summer to fall here. It's a wildflower in Illinois, often found in wet ground, marshes, and fens. Mine grow quite peacefully in the garden with no special HOing consideration. These plants self-seed but mine haven't portrayed any invasive characteristics. Butterflies and hummers are attracted to their flowers and being a relatively late bloomer they can be a major attractant.
Reportedly native Indians (Mesquakies) finely chopped the roots and secretly mixed them into the food of a quarrelsome couple to rekindle love lost. Other tribes used it as a cure for syphilis (probably influencing the siphilitica part of the scientific name) and other ailments.
These plants self-seed but mine haven't portrayed any invasive characteristics. Butterflies and hummers are attracted to their flowers and being a relatively late bloomer they can be a major attractant.

Positive plantaholic186 On Sep 2, 2008, plantaholic186 from Winnetka, IL wrote:

I love this plant, but I warn others that given a wet location, it's an aggressive spreader. I planted one in a very wet area of my garden, and there are seedlings everywhere. They're all blooming, so at least there's that, and they are easy to pull out, so I thin them out periodically. I have some in a full sun, hot, dryish bed that does beautifully, but hasn't spread babies around. I absolutely love this plant though: a beautiful blue.

Positive dkm65 On Aug 16, 2007, dkm65 from Cedar Falls, IA (Zone 4b) wrote:

Intense blue flowers, on the violet side of the color. It mixes well with its sibling, cardinal flower (Lobelia cardinalis), with it similar bloom times and very intense, deep red flower. It doesn't draw hummingbirds like cardinal flower, but they do feed on it.

The plant file notes that it has above average water needs, but this isn't entirely accurate. As with many prairie natives, it can tolerate periods of drought, as it has very deep roots. It does best when it is in a low-lying spot, such as a swale or raingarden, with well-drained but occasionally flooded soil. Ours does fine going several weeks without any rain or watering once established.

Positive Gabrielle On Feb 5, 2006, Gabrielle from (Zone 5a) wrote:

A very pretty, easy to grow plant. Other names include Lobelia syphilitica, Blue Cardinal Flower, Great Lobelia, High Belia. Light aids germination of seeds. Blooms in August - September in my garden.

Neutral JodyC On Jan 17, 2005, JodyC from Palmyra, IL (Zone 5b) wrote:

The flowers attract bumblebees primarily. Less common visitors include hummingbirds, butterflies, and Halictid bees. The latter group of bees collect pollen only and are non-pollinating. Most mammalian herbivores don't eat this plant because the foliage contains several toxic alkaloids, chief among them being lobeline and lobelanine. These toxic substances produce symptoms that resemble nicotine poisoning. However, it has been reported that deer occasionally eat this plant, perhaps enjoying greater immunity to these toxic substances than other animals. The seeds are too small to be of much value to birds.

Positive hanna1 On Oct 4, 2004, hanna1 from Castro Valley, CA (Zone 9a) wrote:

I bought mine in Spring at my favorite nursery in Oakland, I transplanted it in a new pot in semi-shade, got a lot of water, was beautifull, and very blue, I had never seen one before, new plantlets are growing at the base of the original and I can't wait to see it take off again.

Positive lego_brickster On Sep 12, 2004, lego_brickster from Lawrenceville, PA (Zone 5b) wrote:

This is native in my zone 5 area. We found several stalks of it this year growing in the weeds around our pond. It's in full sun, but has very wet feet. It shares the same terrain as our cattails.

We're going to try collecting seeds this year. It would look great in a mass planting. Ours grow in very narrow spikes with little lateral foliage or stalks.

It must spread by seed, but only a little. We find small growths of it here and there in our field.

Positive karenbarnett On Aug 22, 2004, karenbarnett from El Dorado, AR wrote:

Native to my area in southern Arkansas, this beauty thrives in intermittent stream beds, as well a in a pot on my sunny deck. Semi-shade deepens the intensity of the blue.

Positive flowerman On Oct 10, 2003, flowerman from Saint Louis, MO wrote:

I have seen these grow on rock walls along river banks. They are spectacular and inspiring, to say the least!

Positive Karenn On Sep 28, 2003, Karenn from Mount Prospect, IL (Zone 5a) wrote:

I really like this particular variety - it shuffles itself around the planting bed and parks where it is happiest! It is not invasive (like goose-neck loosestrife), just puts a clump or two around the bed. And blooms just when the summer bloomers are fading! What a great plant!

Positive Ladyfern On Aug 7, 2003, Ladyfern from Jeffersonville, IN (Zone 6a) wrote:

Easy from seed--will even bloom a little the first year! Great for the butterflies and hummingbirds. The foliage is a handsome dark green. A group of these is just specatacular in the late summer garden.

Positive lupinelover On Aug 31, 2002, lupinelover from Grove City, OH (Zone 6a) wrote:

This plant is much easier to please than the better-known Scarlet Lobelia, so that most gardeners should be able to find a place for it in their landscape. It tolerates full shade, but blooms much better in full to partial sun.

Positive Terry On Mar 8, 2001, Terry from Murfreesboro, TN (Zone 7a) wrote:

Native to North America, produces spikes of blue flowers in late summer. The plant grows well in moist to wet soils and so is useful near water. The plant may be short-lived but will tend to reseed.


This plant has been said to grow in the following regions:

Auburn, Alabama
Castro Valley, California
Denver, Colorado
Cornwall Bridge, Connecticut
Simsbury, Connecticut
Wilmington, Delaware
Anna, Illinois
Aurora, Illinois
Divernon, Illinois
Itasca, Illinois
Mount Prospect, Illinois
Rockford, Illinois
Wilmette, Illinois
Winnetka, Illinois
Bloomington, Indiana
Jeffersonville, Indiana
Logansport, Indiana
Macy, Indiana
Valparaiso, Indiana
Cedar Falls, Iowa
Derby, Kansas
Shawnee Mission, Kansas
Brandenburg, Kentucky
Hebron, Kentucky
Baltimore, Maryland
Potomac, Maryland
Silver Spring, Maryland
Sharon, Massachusetts
Erie, Michigan
Lake Orion, Michigan
Pinconning, Michigan
Royal Oak, Michigan
Andover, Minnesota
Hopkins, Minnesota
Saint Paul, Minnesota (2 reports)
Byhalia, Mississippi
Florence, Mississippi
Cape Girardeau, Missouri
Cole Camp, Missouri
Piedmont, Missouri
Saint Louis, Missouri
Hudson, New Hampshire
Munsonville, New Hampshire (2 reports)
Browns Mills, New Jersey
Frenchtown, New Jersey
Averill Park, New York
Bronx, New York
Buffalo, New York
Croton On Hudson, New York
Glens Falls, New York
Syracuse, New York
Yonkers, New York
Chapel Hill, North Carolina
Elizabeth City, North Carolina
Belfield, North Dakota
Fremont, Ohio
Glouster, Ohio
Allentown, Pennsylvania
Coopersburg, Pennsylvania
Greensburg, Pennsylvania
Lawrenceville, Pennsylvania
Lehigh Valley, Pennsylvania
Philadelphia, Pennsylvania
Saylorsburg, Pennsylvania
West Chester, Pennsylvania
Wilkes Barre, Pennsylvania
Conway, South Carolina
Murfreesboro, Tennessee
Old Hickory, Tennessee
Austin, Texas (2 reports)
Dallas, Texas
Longview, Texas
Arlington, Virginia
Leesburg, Virginia
Lexington, Virginia
Pearisburg, Virginia
Roanoke, Virginia
Kalama, Washington
Pullman, Washington
Cambridge, Wisconsin
Pleasant Prairie, Wisconsin

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