Cardinal flower Lobelia cardinalis
Cardinal flower (Lobelia cardinalis) is a deciduous perennial flowering plant in the Campanulaceae family, native to The Americas, from south-east Canada to Colombia. It grows 60 cm–1.2 m (24 in–3.9 ft) tall and 30–60 cm (12–24 in) wide, wants part sun to part shade and high water, and is hardy to about -35 °C (-31 °F). Space plants about 30 cm (12 in) apart.
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Cardinal flower at a glance
| Type | Perennial flowering plant, deciduous |
|---|---|
| Family | Campanulaceae |
| Mature height | 60 cm–1.2 m (24 in–3.9 ft) |
| Mature spread | 30–60 cm (12–24 in) |
| Spacing | 30 cm (12 in) centre to centre |
| Sun | Part sun to part shade, at least 4 h of direct sun a day |
| Water | High; drought tolerance none, waterlogging tolerance high |
| Soil pH | 5.5–7.5 |
| Cold hardiness | About -35 °C (-31 °F) once established (roughly USDA zone 3) |
| Heat stress | Likely above about 34 °C (93 °F) |
| Flowering | from about July for 6–9 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | High |
| Edible | Not grown as food |
| Native to | The Americas, from south-east Canada to Colombia |
| Common in gardens of | 🇺🇸 United States, 🇨🇦 Canada, 🇲🇽 Mexico, 🇬🇧 United Kingdom |
Is Cardinal flower toxic?
- People: moderately toxic
- Cats: moderately toxic
- Dogs: moderately toxic
- Parts: all parts
Contains lobeline and related alkaloids.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Cardinal flower
No well-documented helpful pairing. Group it with plants that like part sun to part shade and high water.
Questions about Cardinal flower
- How far apart should I plant Cardinal flower?
- About 30 cm (12 in) apart, centre to centre. A mature plant spreads 30–60 cm (12–24 in).
- Does Cardinal flower need full sun?
- Part sun to part shade: at least 4 hours of direct sun a day.
- How much water does Cardinal flower need?
- High water. Drought tolerance is none and waterlogging tolerance high.
- How cold-hardy is Cardinal flower?
- It tolerates about -35 °C (-31 °F) once established, roughly USDA zone 3.
- When does Cardinal flower flower?
- From about July for 6–9 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Cardinal flower poisonous to cats and dogs?
- For cats it is moderately toxic; for dogs moderately toxic; for people moderately toxic. Contains lobeline and related alkaloids.
- What grows well with Cardinal flower?
- There is no well-documented companion pairing for Cardinal flower. Group it with plants that like the same sun (part sun to part shade) and water (high).
Sources and evidence
Evidence grade A (A: strong evidence).
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- Native Plant Information Network, Lady Bird Johnson Wildflower Center, University of Texas at Austin
Notes and assumptions
- Spikes of intense scarlet flowers by streams and ponds in late summer, pollinated mainly by ruby-throated hummingbirds. Short-lived: let it self-seed.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Canterbury bells Campanula medium
- Edging lobelia Lobelia erinus
- Balloon flower Platycodon grandiflorus
- Fairy's thimble Campanula cochleariifolia
- Deodeok (bonnet bellflower) Codonopsis lanceolata
- Great blue lobelia Lobelia siphilitica
- Dwarf grassy bells (edraianthus) Edraianthus pumilio
- Dalmatian bellflower (wall bellflower) Campanula portenschlagiana