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Lobelia siphilitica (Great Blue Lobelia)

Great Blue Lobelia, Big Blue Lobelia, Blue Cardinal Flower, Blue cardinal flower, Great Lobelia , Tall Blue Lobelia, Virginia Bellflower, Vomit Root

Lobelia Siphilitica, Great Blue Lobelia, Big Blue Lobelia, Blue Cardinal Flower, Blue cardinal flower, Great Lobelia , Tall Blue Lobelia, Virginia Bellflower, Vomit Root, Blue flowers

A North American native that is perfect for the late summer garden, Lobelia siphilitica (Great Blue Lobelia) is a popular, upright perennial that produces long-lasting spikes of bright blue flowers atop finely-toothed, lance-shaped foliage from late summer to mid-fall. Quite an architectural plant that adds vertical interest to the landscape. The nectar and pollen of the flowers attract hummingbirds, bumblebees, and other long-tongued bees primarily. Exceptionally hardy, low care, and fairly pest and disease-free, Great Blue Lobelia tends to be short-lived, although it may self-seed in ideal growing conditions (without becoming invasive).

  • Generally growing 2-3 ft. tall (60-90 cm) and spreading 12-18 in. (30-45 cm), this clump-forming Lobelia thrives in rich, humusy, medium to wet soils in full sun to part shade. Appreciates some shade from the hot afternoon sun and loves a lot of moisture. Keep soil moist during summer dry spells. It can be grown in water to 3 in. deep (7 cm).
  • A welcomed addition to beds, borders, wild gardens, woodland gardens, cottage gardens, and near ponds or streams.
  • A magnet for hummingbirds, butterflies, and beneficial insects, it is deer and rabbit-resistant!
  • Deadhead for a neat appearance, encourage rebloom or prevent any undesired reseeding. Pinch back for bushier and more compact plants. Do not cut back in fall, mulch lightly. Divide clumps in spring if needed.
  • Ingestion may cause discomfort.
  • Toxic to dogs, toxic to cats, toxic to horses.

Requirements

Hardiness 4 - 9
Heat Zones 1 - 8
Climate Zones 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17
Plant Type Perennials
Plant Family Campanulaceae
Genus Lobelia
Common names Lobelia, Great Blue Lobelia
Exposure Full Sun, Partial Sun
Season of Interest Summer (Late)
Fall
Height 2' - 3'
(60cm - 90cm)
Spread 1' - 2'
(30cm - 60cm)
Spacing 12" - 18"
(30cm - 50cm)
Maintenance Low
Water Needs High
Soil Type Chalk, Clay, Loam, Sand
Soil pH Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Moisture Retentive
Characteristics Showy
Native Plants United States, Massachusetts, New York, New Jersey, New Hampshire, Maryland, Connecticut, Maine, Delaware, Vermont, Pennsylvania, Rocky Mountains, Southwest, Southeast, Midwest, Northeast, Kansas, Missouri, Michigan, Illinois, Indiana, Minnesota, Iowa, Wisconsin, South Dakota, Ohio, Nebraska, North Dakota, Kentucky, Georgia, Arkansas, Alabama, West Virginia, Virginia, Tennessee, North Carolina, Mississippi, Louisiana, South Carolina, Texas, Oklahoma, Wyoming, Colorado
Tolerance Deer, Wet Soil
Attracts Bees, Birds, Butterflies, Hummingbirds
Garden Uses Beds And Borders, Bog Gardens, Ponds And Streams, Rain Gardens, Water Gardens
Garden Styles Prairie and Meadow, Informal and Cottage, Coastal Garden, City and Courtyard
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Alternative Plants to Consider

Lobelia x speciosa ‘Starship Deep Rose’ (Cardinal Flower)
Lobelia cardinalis ‘Queen Victoria’ (Cardinal Flower)
Lobelia erinus (Trailing Lobelia)
Lobelia x speciosa ‘Vedrariensis’ (Cardinal Flower)
Lobelia cardinalis (Cardinal Flower)

Recommended Companion Plants

Allium schoenoprasum (Chives)
Pennisetum setaceum ‘Rubrum’ (Purple Fountain Grass)
Rudbeckia hirta ‘Prairie Sun’ (Black-Eyed Susan)

Find In One of Our Guides or Gardens

Best Flowers to Attract Hummingbirds
While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.
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Requirements

Hardiness 4 - 9
Heat Zones 1 - 8
Climate Zones 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17
Plant Type Perennials
Plant Family Campanulaceae
Genus Lobelia
Common names Lobelia, Great Blue Lobelia
Exposure Full Sun, Partial Sun
Season of Interest Summer (Late)
Fall
Height 2' - 3'
(60cm - 90cm)
Spread 1' - 2'
(30cm - 60cm)
Spacing 12" - 18"
(30cm - 50cm)
Maintenance Low
Water Needs High
Soil Type Chalk, Clay, Loam, Sand
Soil pH Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Moisture Retentive
Characteristics Showy
Native Plants United States, Massachusetts, New York, New Jersey, New Hampshire, Maryland, Connecticut, Maine, Delaware, Vermont, Pennsylvania, Rocky Mountains, Southwest, Southeast, Midwest, Northeast, Kansas, Missouri, Michigan, Illinois, Indiana, Minnesota, Iowa, Wisconsin, South Dakota, Ohio, Nebraska, North Dakota, Kentucky, Georgia, Arkansas, Alabama, West Virginia, Virginia, Tennessee, North Carolina, Mississippi, Louisiana, South Carolina, Texas, Oklahoma, Wyoming, Colorado
Tolerance Deer, Wet Soil
Attracts Bees, Birds, Butterflies, Hummingbirds
Garden Uses Beds And Borders, Bog Gardens, Ponds And Streams, Rain Gardens, Water Gardens
Garden Styles Prairie and Meadow, Informal and Cottage, Coastal Garden, City and Courtyard
How Many Plants
Do I Need?
Explore Great Plant Combination Ideas
Lobelia
Guides with
Lobelia
Not sure which Lobelia to pick?
Compare Now

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