Lobelia siphilitica (Blue Lobelia)

The true-blue counterpart to cardinal flower, blue lobelia pairs beautifully with its red relative for a striking late-season color combination that draws bumblebees, long-tongued bees, and hummingbirds together - a reliable, colony-forming addition to any consistently moist planting.

Species Overview

Lobelia siphilitica is a perennial wildflower native to wetlands, meadows, and streambanks in North America. Growing 2 to 3 feet tall, it features dense terminal spikes of bright blue, tubular, two-lipped flowers blooming from late summer to early fall. It is the bluish counterpart to cardinal flower, and is somewhat more drought tolerant than that species, though still not a dry-site plant.

Application

• Wetland, rain garden, and pond-margin plantings
• Paired plantings with Lobelia cardinalis for a red-and-blue late-season display
• Wet meadow and woodland-edge naturalizing
• Pollinator habitat - bumblebees, long-tongued bees, and hummingbirds

Growing Conditions / Specification Data

• Light: Full Sun to Full Shade
• Soil/Moisture Tolerance: Moist to wet soils; more drought tolerant than Lobelia cardinalis, but not a dry-site plant
• Drought Tolerance: Low
• Flood Tolerance: High - Rated FACW+ (leaning Obligate Wetland) - usually occurs in wetlands.
• Plant Type: Forb
• Mature Height: 2-4 ft.
• Fall Color: Insignificant/None
• Bloom Color / Period: Blue, Purple; July-October
• Wetland Indicator Status: NI (No Indicator) - see flags
• Native Range: Eastern North America
• Hydrology: Moist-Wet
• Root Depth: Moderate (12-24 in.)
• Salinity Tolerance: Low
• Growth Rate: Moderate
• Deer Resistance: Yes (Rarely Damaged)
• Shade Tolerance: Tolerant
• Growth Habit: Clumping/Mounding
• USDA Hardiness Zones: 4-9
• Pollinator Value: Supports bees, supports butterflies, supports hummingbirds

Planting Guidance

• As with other Lobelia species, the flowering stem and roots die after seed is produced; new offsets form nearby and should not be buried under thick winter mulch.