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Lobelia siphilitica (Blue cardinal flower, Great blue lobelia)

Lobelia siphilitica Photo/Illustration: Courtesy of Bluestone Perennials


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Hardiness Zones: 1 2 3 4 5 6 7 8 9 10 11
Botanical Name: Lobelia siphilitica lo-BEE-lee-ah sif-il-IT-ih-kah Common Name: Blue cardinal flower, Great blue lobelia Genus: Lobelia
This clump-forming perennial has upright leafy stems. From late summer to mid-autumn, it bears dense spikes of light to bright blue tubular, two-lipped flowers with a more prominent lower lip.
Noteworthy characteristics: Long-lasting bloom. Suitable for edging, near water, or in a mixed or herbaceous border. U.S. native.
Care: Grow in deep, moist soil. Fertilize every two weeks in spring and early summer to improve flowering. Plants may be trimmed as they die back in hot summers.
Propagation: Divide in summer. Take bud cuttings in midsummer.
Problems: Rust, smut, leaf spots, and slugs.
Height 1 ft. to 3 ft.
Spread 6 in. to 12 in.
Light Full Sun to Part Shade
Moisture Medium to Wet
Maintenance Moderate
Characteristics Native; Showy Flowers
Bloom Time Fall; Summer
Flower Color Blue Flower; Purple/ Lavender Flower
Uses Beds and Borders, Naturalizing, Waterside
Seasonal Interest Summer Interest, Fall Interest
Type Perennials

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