General Plant Information (Edit)
Plant Habit: Herb/Forb
Life cycle: Perennial
Sun Requirements: Full Sun to Partial Shade
Water Preferences: Wet
Wet Mesic
Mesic
Minimum cold hardiness: Zone 4b -31.7 °C (-25 °F) to -28.9 °C (-20 °F)
Plant Height: 3 to 5 feet
Flowers: Showy
Flower Color: Blue
Bloom Size: Under 1"
Flower Time: Late summer or early fall
Underground structures: Taproot
Uses: Erosion control
Water gardens
Will Naturalize
Wildlife Attractant: Bees
Birds
Hummingbirds
Resistances: Deer Resistant
Rabbit Resistant
Flood Resistant
Humidity tolerant
Toxicity: Other: milky juice from plant considered somewhat poisonous.
Propagation: Seeds: Provide light
Stratify seeds: 2 months cold moist treatment
Depth to plant seed: Seed is tiny. Do not cover with soil; keep moist.
Can handle transplanting
Propagation: Other methods: Division
Pollinators: Bees

Image
Common names
  • Great Blue Lobelia
  • Blue Cardinal Flower
Botanical names
  • Accepted: Lobelia siphilitica
  • Synonym: Lobelia siphilitica var. rosea
  • Synonym: Lobelia siphilitica var. ludoviciana
  • Synonym: Lobelia siphilitica var. siphilitica

Photo Gallery
Location: Vermont
Date: 2017-09-08
Location: Carter Caves State Park, Olive Hill, KY
Date: 2017-09-17
Location: Willow Valley Communities Lakes Campus,Willow Street, Pennsylvania
Date: 2023-09-03
Location: St Louis
Date: 2022-09-13
Location: My garden, Pequea, Pennsylvania, USA
Date: 2018-08-11
Do you see the tiny pollinator?
Location: central Illinois
Date: 8-25-19
Location: Brownstown PA 17508
Date: 2018-08-15
Location: Indiana zone 5
Date: 2014-08-21
Location: Indiana zone 5
Date: 2014-08-21
Location: central Illinois
Date: 2016-07-31
Location: St Louis
Date: 2019-09-14
Location: Indiana zone 5
Date: 2014-08-03
emerging flower head

Date: 2022-05-14
Location: central Illinois
Date: 2011-09-25
in the wild
Location: My Northeastern Indiana Gardens - Zone 5
Date: 2011-10-22
Location: central Illinois
Date: 9-20-11
Location: Mentor on the Lake
Date: 2018-08-03
Location: Maryland
Date: 2015-07-19
Location: Kalama, Wa
Date: 2010-08-22
  • Uploaded by Joy

Date: 2008-09-04
Location: Fairfax, Virginia (May 2022)
Date: 2022-05-25
Location: Perelman Park, Manheim Township, Lancaster County Pennsylvania
Date: 2016-08-12
Location: Brownstown Pennsylvania
Date: 2015-08-31
Uploaded by SongofJoy

Date: 2015-08-03
Location: Eagle Bay, New York
Date: 2022-08-10
Great Blue Lobelia (Lobelia siphilitica) in a patch
Location: Eagle Bay, New York
Date: 2022-08-10
Great Blue Lobelia (Lobelia siphilitica) blooms are deeply blue
Uploaded by purpleinopp
Location: Nora's Garden - Castlegar BC
Date: 2016-07-27
 9:19 am. A beautifully structured blue blossom.
Location: Maryland
Date: 2014-08-19
Location: Kamloops, BC, Canada
Date: 2012-10-21
Location: Chicago Botanic Garden
Date: 2018-09-01
Location: Chicago Botanic Garden
Date: 2018-09-01
Location: My Northeastern Indiana Gardens - Zone 5b
Date: 2012-07-04
Location: IL
Date: 2009-09-22
Location: central Illinois
Date: 2016-09-27
Location: My Northeastern Indiana Gardens - Zone 5
Date: Sep 22, 2011 1:57 PM
Location: Allentown, Pennsylvania
Date: 2015-08-06
Location: Maryland
Date: 2015-07-24
Location: central Illinois
Date: 8-31-07
Location: Tennessee
photo courtesy of Sunlight Gardens, www.sunlightgardens.com

Photo Courtesy of Prairie Nursery. Used with Permission
  • Uploaded by Joy
Location: English Gardens, Dearborn Heights, MI
Date: 2017-09-09
Location: central Illinois
Date: 2010-09-08
Location: Vermont
Date: 2016-08-23
Location: Telly's Greenhouse, Troy, MI
Date: 2013-09-19
Location: In my garden in Kalama, Wa.
Date: 2006-08-27
  • Uploaded by Joy
Location: St Louis
Date: 2019-09-14
Location: My Northeastern Indiana Gardens - Zone 5b
Date: Sep 26, 2011 3:46 PM
Location: Ingleside. Illinois
Date: 2023-05-27
Location: Lucketts, Loudoun County, Virginia
Date: 2011-09-16
Location: central Illinois
Date: August 2009
Location: My Northeastern Indiana Gardens - Zone 5
Date: Aug 14, 2011 8:19 AM
Uploaded by purpleinopp
Location: Nora's Garden - Castlegar BC
Date: 2016-05-10
 6:19 pm. Always a welcome sight to see the self-seeding of this
Location: central Illinois
Date: 2016-07-19
Location: My Northeastern Indiana Garden - Zone 5b
Date: Sep 20, 2011 11:51 AM
Rosette Stage
Location: Indiana  Zone 5
Date: Aug 3, 2010 1:26 PM
close-up
Location: My Northeastern Indiana Garden - Zone 5b
Date: Sep 22, 2011 1:59 PM
Pre-bloom
Location: In my garden in Kalama, Wa.
  • Uploaded by Joy
Location: the Lurie Garden in Chicago, Illinois
Date: 2013-08-13
nice group in bloom
Location: West Chester, Pennsylvania
Date: 2016-08-29
group of blue and white bloomers in landscape
Location: Glen Ellyn, Illinois
Date: 2012-08-15
group in bloom with boulders
Location: Lancaster County, Pennsylvania
Date: 2013-07-26
several plants in bloom in garden

Photo Courtesy of Lazy S'S Farm Nursery.
  • Uploaded by Joy

Photo Courtesy of Lazy S'S Farm Nursery.
  • Uploaded by Joy
Location: central Illinois
Date: 8-31-06
behind coleus
Location: central Illinois
Date: 9-8-06
w/ night moth
Location: central Illinois
Date: 2012-07-26
Location: central Illinois
Date: 2011-09-20
Location: Kalama, Wa.
  • Uploaded by Joy
Location: central Illinois
Date: 2013-09-01
Location: central Illinois
Date: 2011-09-10
Location: English Gardens, Dearborn Heights, MI
Date: 2017-09-09
Location: English Gardens, Dearborn Heights, MI
Date: 2017-09-09
Location: English Gardens, Dearborn Heights, MI
Date: 2017-09-09
Location: Telly's Greenhouse, Troy, MI
Date: 2013-09-19
Location: Indiana  Zone 5
Date: September
Location: Telly's Greenhouse, Troy, MI
Date: 2013-09-19
Location: Telly's Greenhouse, Troy, MI
Date: 2013-09-19
Location: Telly's Greenhouse, Troy, MI
Date: 2013-09-19
Location: central Illinois
Date: 2015-09-05
Location: central Illinois
Date: 2015-09-09
Location: Indiana zone 5
Date: 2014-08-03
Location: central Illinois
Date: 2015-10-20

Courtesy Crownsville Nursery
  • Uploaded by vic

Courtesy Crownsville Nursery
  • Uploaded by vic
Location: central Illinois
Date: 2016-07-19
This plant is tagged in:
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Comments:
  • Posted by ILPARW (southeast Pennsylvania - Zone 6b) on Feb 20, 2018 3:13 PM concerning plant:
    This Great Blue Lobelia is a glorious perennial for moist or draining wet soils that prefers some partial shade, but can do full sun in moist soils. It is a long bloomer in August into early October. It is an easy and reliable plant, but it does not like strong completion from bigger plants. It often self-sows a lot, even getting seedlings into nearby pots. It is longer lived than the similar Cardinalflower. It is easy to transplant with shallow fibrous roots. In fact, I can pull plants right out of the ground without digging for transplanting and then just plant them as is. Some are sold by many conventional, classic nurseries and by most native plant nurseries. I have not seen this species sold by big box or Home Depot-Lowes stores. I find it occasionally planted around in yards; it should be used much more. It is a very easy perennial. Its native range is from Maine to southern Manitoba to Colorado into Texas through Alabama to North Carolina.
  • Posted by jmorth (central Illinois) on Nov 10, 2011 1:41 AM concerning plant:
    Habitat - Wildflower that grows in wet ground, marshes, fens, and open woodlands along streams.
    Mesquakies Indians thought it could heal failing relationships if added, unbeknownst to the quarreling couple's food.
    Some Indians believed it a cure for syphilis. The 'secret' was sold to some Europeans who took it to Europe where it failed to perform to expectations.
    Genus named in honor of a 16th century herbalist, Matthias de l'Obel.
  • Posted by jmorth (central Illinois) on Oct 30, 2011 2:51 PM concerning plant:
    Likes wet ground, marshes, and fens.
    Mesquakies Indians thought that chopping the roots and mixing them into food of quarrelsome couples without their knowledge would avert divorce and cause the pair to love again.
  • Posted by Catmint20906 (PNW WA half hour south of Olympia - Zone 8a) on Aug 24, 2014 6:29 AM concerning plant:
    Great Blue Lobelia (Lobelia siphilitica) is a beautiful late-summer perennial native to eastern North America. Lobelia siphilitica has special value to native and bumble bees. It attracts several bee species, including digger, yellow-faced, green sweat, small carpenter, and bumble bees. Bumble bees in particular like to visit this plant and are its most frequent pollinators. This plant also supports conservation biological control by attracting beneficial insects to the garden. In addition, Great Blue Lobelia attracts hummingbirds.
  • Posted by sallyg (central Maryland - Zone 7b) on May 13, 2019 7:02 AM concerning plant:
    I got this from a swap several years ago. The original plant grows in a very moist spot. I have moved a few into other garden sites as well. I can't say if it prefers one site over another. It has a lot of flowers, on which I noticed one tiny unusual type bee or wasp.
  • Posted by sallyg (central Maryland - Zone 7b) on May 14, 2020 7:44 PM concerning plant:
    Pretty wildflower, I did not see a big variety of insects using it but did watch one certain type of bee that loved it. Makes a lot of seed, somehow had a few volunteers elsewhere in my yard last year. Sorry to say I don't think I have seen any yet this year, I do hope I have some.
Plant Events from our members
gardengus On August 18, 2014 Bloomed
Full
chelle On October 28, 2014 Harvested
Seed collected.
Catmint20906 On July 17, 2015 Bloomed
lovesblooms On January 25, 2015 Seeds sown
winter sown
aspenhill On May 7, 2016 Obtained plant
NGA Susan (Muddy1) - qty 3
christine2 On May 25, 2019 Obtained plant
3 Humber Nursery Ont.
antsinmypants On February 28, 2023 Seeds sown
WS Very few seeds.
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