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