Lobelia cardinalis
Cardinal flower is a moisture loving perennial prized for tall spikes of scarlet red blooms. Plants grow 2 to 4 feet tall and flower from mid to late summer. It thrives in full sun to part shade with constantly moist to wet soil. It is short lived in dry or thin soils and benefits from a cool root run. It is hardy through cold winters across much of North America when soil stays moist. Hummingbirds and butterflies visit the flowers readily.
At‑a‑glance
- Group/Class: Species; herbaceous perennial
- Height × spread: 24-48 in (60-120 cm) × 12-24 in (30-60 cm)
- Bloom window: July to September
- Color & flower form: Scarlet red tubular flowers on upright racemes
- Fragrance: 0 none
- USDA hardiness: zones 3-9
- Breeder / Year / Origin: wild species; unknown; Americas
- Pet safety: avoid
How it differs
- Blooms earlier and in red compared with the blue flowers of Great Blue Lobelia.
- Can reach 4 feet in good soils, so it may stand taller than Great Blue Lobelia.
- Somewhat shorter‑lived and more sensitive to drought.
- Equally adapted to wet or boggy sites when moisture is constant.
Strengths
- Striking vertical color for mid to late summer.
- Excellent for hummingbirds in moist gardens.
- Tolerates wet soil and brief flooding.
Care in one minute
- Site and light: full sun to part shade; afternoon shade helps in hot regions.
- Soil and pH: rich, evenly moist to wet soil; good organic matter.
- Watering: do not allow soils to dry; irrigate during droughts.
- Feeding: compost in spring; avoid excessive fertilizer.
- Grooming: remove spent spikes to tidy; divide clumps in spring if needed.
- Overwintering: apply a light root mulch in cold winters to limit heaving.
Watch‑outs
- Requires steady moisture; plants decline if soils dry.
- Often short‑lived; divide or replant every few years.
- Slugs and snails may damage foliage.
- Mulch in cold climates to reduce frost heave.
Best uses (tags)
rain gardens, pond margins, wildlife‑friendly, borders
Provenance note
A species native to the Americas, common along streams, springs, and wet meadows.
References
- Missouri Botanical Garden Plant Finder – Lobelia cardinalis
- University of Florida IFAS Extension – Cardinal Flower (AG402)
- ASPCA – Lobelia (toxicity to pets)
- Lady Bird Johnson Wildflower Center – Lobelia cardinalis
Written by: Your Flowers Guide editorial team
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