Blue Cardinal Flower (Lobelia siphilitica)
[lo-BEE-lee-ah sif-il-IT-ih-kah]

Deciduous Perennial Mounded in the Campanulaceae Family
Blue Cardinal Flower enchants with its striking blue blooms, creating a stunning contrast in any garden. This perennial thrives in wet areas, attracting pollinators while adding a touch of elegance to your landscape.

Great Blue Lobelia (Lobelia siphilitica) is an upright, usually unbranched herbaceous perennial reaching 2 to 4 feet tall. Showy, bright blue (occasionally white) tubular flowers crowd the upper stem in the leaf axils, each split into two lips -- the upper with two lobes, the lower with three -- and striped on the tube. Its flowers are larger than those of most other Lobelia species. Blooms open in mid-summer and continue into early fall, native to moist meadows, streambanks, and pond edges across much of eastern and central North America, including Illinois.

Pros

  • North American and Illinois native
  • Attracts hummingbirds, bees, and butterflies
  • Self-seeds to form naturalized colonies in the right spot

Cons

  • Needs consistently moist soil -- not drought tolerant
  • Toxic if ingested (see Allergy Notes)
  • Can self-seed more than some gardeners want
 

Plant Data

Mature Size 24 - 36 inches tall. 12 - 18 inches wide.
Sun Exposure Partial Shade - Full Sun
Moisture Tolerance Medium - Wet: Plants tolerate sunny sites if sufficient moisture is present.
Zones 4a - 9b (Usually hardy to -30° F)
Tags Attracts Bees, Attracts Beneficial Insects, Attracts Birds, Attracts Butterflies, Attracts Hummingbirds, Attracts Pollinators, Attracts Wildlife, Colorful Foliage, Container, Deciduous, Deer Resistant, Drought Tolerant, Edging, Formal Garden, Fragrant Flowers, Full Sun, Good for Accents, Good for Beginners, Good for Borders, Good for Butterfly Garden, Good for Cottage Garden, Good for Cut Flowers, Good for Rain Garden, Good for Rock Garden, Illinois Native, Low Maintenance, Medium, Most Popular, Native to North America, Naturalizing, Normal Soil, Partial Shade, Partial Sun, Perennial, Pond, Popular For Fall, Prairie Garden, Rabbit Resistant, Shade Tolerant, Showy Flowers, Tolerant of Clay Soil, Tolerant of Moist Soil, Tolerant of Sandy Soil, Well-Drained Soil, Wet, Wet Site Tolerant, Woodland Garden
Bloom Period July to October
Flower Color Blue
Animals That Use It

Flowers:

Nectar:
 

Most Popular Plants
 

More Info from Experts

Commonly Planted with...

Bee Balm, Black-eyed Susan, Wild Bergamot, Ironweed, Swamp Milkweed, Blue Flag Iris, New England Aster, Cardinal Lobelia, Culver's Root.

Photos of This with...

Joe Pye Weed
 
Want More photos of this plant? Try Google Image Search!
 


Pricing and Availability History

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Past Availability
2025 : 04/03 - 10/04
2024 : 05/01 - 10/05
2023 : 04/13 - 09/30


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Field-Grown vs. Greenhouse-Grown Plants

Plants which are well-adapted to our local climate are most often field-grown (outside). Field-grown plants are generally cheaper and have the advantage of already somewhat acclimated to our cold winters, but that means they’re not artificially far along in the spring and tend to bloom at the normal time in our area.

Spring annuals and tender perennials are typically grown in Greenhouses so they can be ready and luxurious exactly when customers want them. Some perennials are also “forced” into early bloom in greenhouses. In May, there can be a very big difference between field-grown and greenhouse-grown plants of the same type. The latter typically look good right away (so they’re a great choice where that’s important), but we typically pay a premium for it.


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To secure the best prices for club members and make sure we know the current plants available from each nursery, we take orders only a couple of times a month.

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No Pricing or Availability Right Now

We order from a rotating cast of the best nurseries in the Great Lakes region. It looks like we've offered this plant in the past, but the nurseries we're working with this week don't appear to have it in stock at the moment.

Our goal is to bring as many plants together under "one roof" as possible, so we'll try hard to make it available again in the future!