Overview
Lobelia (Lobelia cardinalis and hybrids), commonly called Cardinal Flower, produces brilliant upright spikes of tubular flowers that are unmatched for attracting hummingbirds. The Starship Scarlet variety features deep red blooms on compact, well-branched plants from midsummer through fall. Native to North America and a standout in naturalistic, rain garden, and woodland settings.
Sun & Exposure
- Ideal: Part shade to full sun with consistent moisture
- Best: Morning sun with afternoon shade in hot climates
- Tolerated: Full sun if soil is kept consistently moist
- Leaf scorch occurs in hot afternoon sun without adequate moisture
Watering
Moisture is essential — this is not a drought-tolerant plant.
- Keep soil consistently moist; this is one perennial that tolerates wet conditions
- Ideal near ponds, streams, or rain gardens
- Mulch heavily to retain moisture
- Do not allow to dry out, especially in summer heat
Soil & Planting
- Rich, moist, humus-rich soil
- Slightly acidic pH (5.5–6.5)
- Plant in spring after frost; space 12–18 inches apart
- Shallow roots — do not cultivate around plants
Fertilizing
- Apply a balanced slow-release fertilizer in early spring
- Monthly liquid feeding during the growing season promotes vigorous growth
Pruning
- Deadhead spent spikes to encourage side branching and prolonged blooming
- Cut back to basal rosette after blooming
- Self-sows readily; thin seedlings in spring
Winter Care
Hardy in zones 3–9. The central crown may die after blooming, but offsets and self-sown seedlings maintain the colony. Mulch crowns after frost in colder zones.
Common Issues
Problem
Crown dies after blooming
Cause
Normal behavior — relies on offsets and self-seeding
Problem
Slugs
Cause
Common in moist conditions; use slug controls
Problem
Leaf scorch
Cause
Insufficient moisture or too much direct sun
Problem
Short-lived
Cause
Normal; allow to self-seed for continuity
Tips
- The top plant for attracting Ruby-throated Hummingbirds
- Excellent for rain gardens, pond edges, and bog gardens
- Toxic if ingested — handle with care
- Combines beautifully with Astilbe, ferns, and Monarda in moist borders