General Plant Information (Edit)
Plant Habit: Herb/Forb
Life cycle: Perennial
Sun Requirements: Full Sun to Partial Shade
Water Preferences: Wet
Wet 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
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

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

This plant is tagged in:
Image Image Image

  • 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 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.
Plant Events from our members
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.
» Post your own event for this plant

« Add a new plant to the database

« The Plants Database Front Page