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,
Purple
Uses
Beds and Borders,
Naturalizing,
Waterside
Seasonal Interest
Summer Interest
Type
Perennials

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