Lobelia cardinalis, cardinal flower
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Perennials

Lobelia cardinalis

cardinal flower

CampanulaceaeEastern and central North America

At a Glance

TypePerennial
HabitUpright
FoliageDeciduous
Height24-48 inches (60-120 cm)
Width12-18 inches (30-45 cm)

Growing Zones

USDA Hardiness Zones

3 - 9
Zone 3
Zone 4
Zone 5
Zone 6
Zone 7
Zone 8
Zone 9
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Attracts Pollinators
Attracts Hummingbirds
Native to North America
Maintenancemoderate

Overview

An upright, short-lived native perennial in the family Campanulaceae, native to moist meadows, stream banks, seeps, and wet woodland edges across eastern and central North America. Plants form clumps of basal rosettes that overwinter, sending up erect stems 24–48 inches (60–120 cm) tall in summer, clothed in alternate, lance-shaped leaves 2–5 inches (5–13 cm) long, medium to dark green and often tinged reddish-bronze, especially in red-leaved cultivars. From midsummer through early fall, terminal racemes 8–18 inches (20–45 cm) long bear densely packed, intensely scarlet-red, two-lipped tubular flowers 1.5 inches (4 cm) long with a distinctive three-lobed lower lip and two erect upper petals. The vivid red color is one of the most saturated in the temperate perennial palette. Cardinal flower is a primary nectar source for ruby-throated hummingbirds during their late-summer southward migration. Plants are short-lived (2–4 years) but self-seed in suitable moist conditions and produce offsets that maintain the colony. All parts of the plant are toxic if ingested — an alkaloid, lobeline, causes symptoms similar to nicotine poisoning.

Native Range

Native to eastern and central North America from New Brunswick and Quebec south to Florida and west to Nebraska and Texas, growing in wet meadows, stream banks, marshes, pond edges, and moist open woodland clearings, typically in full sun to partial shade.

Suggested Uses

Planted at pond margins, in bog gardens, rain gardens, and moist perennial borders at 12–18 inch (30–45 cm) spacing. An essential plant for hummingbird gardens, particularly in eastern North America where it is the primary mid-late summer hummingbird nectar source. Effective combined with Eutrochium (Joe-pye weed), Lobelia siphilitica (blue lobelia), and native ferns in naturalistic moist plantings.

How to Identify

Identified by erect stems 24–48 inches (60–120 cm) bearing terminal racemes of intensely scarlet-red two-lipped tubular flowers 1.5 inches (4 cm) long with three spreading lower lobes and two erect upper petals. The brilliant, saturated red color, combined with the distinctive two-lipped tubular flower form and the moist-site preference, is diagnostic. Leaves may be reddish-bronze, especially in colored-foliage selections.

Appearance

Size & Dimensions

Height2' - 4'
Width/Spread1' - 1'6"

Colors

Flower Colors

red

Foliage Colors

green
red

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~8 weeks
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SummerFall
Blooms July through September in zones 3–9, with peak bloom in August. The raceme opens progressively from the base upward over 4–6 weeks. Individual flowers last 4–7 days. In the Pacific Northwest, bloom peaks mid-July through late August. Hummingbirds visit continuously during the bloom period.

Detailed Descriptions

Flower Description

intensely scarlet-red

Foliage Description

medium to dark green, often tinged reddish-bronze; lance-shaped

Growing Conditions

Sun Requirements

Full Sun
Partial Shade
Requires 4-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)
357912
Soil Types
loamclaypeat
Drainage
wet

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

1 year

Care & Maintenance

Care Guide

Plant in partial shade to full sun in consistently moist to wet, humus-rich, fertile soil with a pH of 5.5–7.0. Requires reliable moisture throughout the growing season — plants wilt and decline rapidly in dry soil. Ideal for bog gardens, rain gardens, pond margins, and consistently moist perennial borders. Apply a 2–3 inch (5–8 cm) mulch layer to retain moisture. In zones 3–5, mulch the crown in fall to protect overwintering rosettes. Plants are short-lived; allow self-seeding and divide offsets in early spring every 2–3 years to maintain colony vigor. All parts toxic if ingested.

Pruning

Leave the spent raceme to set seed if self-seeding is desired for colony renewal — seeds germinate freely in moist soil. Alternatively, cut back the spent spike to the crown rosette after bloom if spread control is needed. In fall, cut stems to ground level after frost. Separate and replant offset rosettes in early spring — each rosette will produce a flowering stem the following year. Divide every 2–3 years.

Pruning Schedule

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fallearly spring

Maintenance Level

moderate

⚠️ Toxicity Warning

Toxic to humans