Does it need full sun?

It prefers full sun to partial shade, provided the soil stays consistently moist.

Can I grow it in a pot?

Yes, but you must keep the pot sitting in a tray of water to mimic its native wetland habitat.

Plant guide

Cardinal flower.

Lobelia cardinalis

Pronounced loh-BEE-lee-uh kar-din-AL-iss

Also known as Cardinal-flower, Cardinalflower, Scarlet Lobelia, cardinal flower

The cardinal flower is a stunning native perennial that loves to hang out in moist, boggy areas. It produces tall spikes of vibrant, deep red flowers that are absolute magnets for hummingbirds. It is a fantastic choice if you have a damp spot in your garden that needs a pop of color.

Another photo of Cardinal flower — Photo by mfeaver (CC BY) via gbif

At a glance

Care level: Moderate
Plant type: Perennial
Light: Full sun to partial shade
Indoor light: Bright indirect
Water: Every 1 to 3 days
Mature size: 4 feet
Growth rate: Medium
Hardiness: USDA 2 to 9
Bloom time: Mid to late summer

Care

Keep the soil consistently moist because this plant hates to dry out. Watch for wilting leaves as a sign that it needs more water. It thrives best when it gets plenty of light but is protected from the harshest afternoon sun.

Watering: Keep the soil constantly damp, never allowing it to dry out completely.
Feeding: Apply a balanced liquid fertilizer during the active growing season.
Pruning: Cut the stems back to the ground after the plant finishes blooming in late autumn.
Repotting: Repot if the plant becomes root bound or if the soil loses its ability to retain moisture.
Soil: Rich, moist, organic soil
Soil pH: 6.0 to 7.5
Temperature: -30 to 35°C
Humidity: 60 to 90%
Drought tolerance: Low
Lifespan: Short lived perennial, typically 3 to 5 years.
Deer and rabbits: Moderate

Signs it needs repotting

Roots growing out of the drainage holes.
The plant stops blooming well.
The soil dries out too quickly.

Safety

People: All parts of the plant are toxic if consumed and may cause nausea or vomiting.
Pets: This plant is toxic to cats and dogs if ingested.
Children: Keep this plant away from small children as ingestion of any part can cause illness.
Contact allergens: The sap can be irritating to sensitive skin.
Airborne allergens: There are no significant reports of airborne allergens.
Edibility: This plant contains lobeline and other alkaloids which are toxic if ingested.

How to identify it

Tall spikes of brilliant red flowers
Lance shaped dark green leaves
Stems grow up to four feet
Flowers have five distinct petals

Height: 0.6 to 1.2m
Spread: 0.3 to 0.6m
Leaves: green, bronze, deciduous
Flowers: red, 2 to 4cm

Problems to watch for

Root RotCommon
Slugs and SnailsCommon
AphidsUncommon
Botrytis BlightUncommon

By symptom

Plant problems by symptom

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Growing it

Propagation: division, seed, cuttings
When to plant: spring, fall
Overwintering: Ensure the crown is not buried too deep and keep the soil moist but not frozen solid in standing water. A light mulch can help protect the roots in colder climates.
In containers: It grows well in containers if kept in a water garden or a saucer of water, with a minimum pot size of 20 centimeters.

Division

1. Dig up the clump in early spring.
2. Gently pull the offsets apart.
3. Replant immediately in moist soil.

Seed

1. Surface sow seeds in late winter.
2. Keep the soil consistently wet.
3. Provide bright light for germination.

Group these with other moisture loving perennials to ensure they all receive the water they need without drying out.

Grows well with

Blue Lobelia · They share similar moisture requirements and bloom at the same time.
Turtlehead · This plant also loves wet soil and provides a nice textural contrast.
Joe Pye Weed · It creates a beautiful height contrast in a rain garden setting.

Similar species

Blue Lobelia · It is a close relative with similar growth habits but blue flowers.

Science

Family: Campanulaceae
Genus: Lobelia
Order: Asterales
Class: Magnoliopsida
Native range: North America
Conservation: It is not currently listed as endangered, but it should never be collected from the wild.

It thrives in damp, low lying areas where its roots can remain saturated throughout the growing season.

Value to wildlife: nectar source, attracts hummingbirds
Pollinators: hummingbirds, butterflies, bees
Uses: rain gardens, bog gardens, pollinator borders

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 1/9
Soil reaction: 5/9
Light: 6/9
Temperature: 5/9
Moisture: 8/9
Nutrients: 5/9

Taxonomy resolved against GBIF.

Questions people ask

Does it need full sun?: It prefers full sun to partial shade, provided the soil stays consistently moist.
Can I grow it in a pot?: Yes, but you must keep the pot sitting in a tray of water to mimic its native wetland habitat.

Where the name comes from

The name cardinalis refers to the vibrant red color, which resembles the robes worn by Catholic cardinals. The genus honors the Belgian botanist Matthias de l'Obel.

Good to know

It is a classic choice for hummingbird gardens.
The plant naturally grows in wet, marshy areas.
It is a short lived perennial that often reseeds itself.

Also in

Plants toxic to cats and dogs

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.