Blue cardinal flower

Lobelia siphilitica

Photo/Illustration: 
Courtesy of Bluestone Perennials
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Blue cardinal flower (Lobelia siphilitica)
lo-BEE-lee-ah sif-il-IT-ih-kah
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.

Overview

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
Type
Perennials

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