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Cardinal Flower

Lobelia cardinalis

brown humming bird flying near red flowers

Nature's most brilliant red wildflower creates an unforgettable display with its intense scarlet blooms that seem to glow in shade gardens. This native beauty is a hummingbird magnet, drawing ruby-throated hummingbirds from miles around with its tubular flowers perfectly designed for their long beaks. Thriving in moist soils where many plants struggle, it brings vibrant color to pond edges, rain gardens, and woodland borders.

Sun

Full sun to partial shade

☀️

Zones

3–9

USDA hardiness

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Height

4-5 feet

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Planting Timeline

Zone:

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Transplant

Direct Sow

Transplant

Direct Sow

Showing dates for Cardinal Flower in USDA Zone 7

All Zone 7 native-wildflower →

Zone Map

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Cardinal Flower · Zones 3–9

What grows well in Zone 7? →

Growing Details

Difficulty

Easy

Spacing12-18 inches

SoilRich, moist to wet, organic soil

pH6.0-7.5

WaterModerate — regular watering

SeasonSpring

FlavorN/A

ColorBrilliant scarlet red

Size12-18 inch flower spikes

Zone-by-Zone Planting Calendar

Zone	Indoor Start	Transplant	Direct Sow	Harvest
Zone 3	—	June – August	May – July	—
Zone 4	—	June – July	April – June	—
Zone 5	—	May – July	April – June	—
Zone 6	—	May – July	April – June	—
Zone 7	—	May – June	March – May	—
Zone 8	—	April – June	March – May	—
Zone 9	—	March – May	February – April	—

Complete Growing Guide

Light: Dappled Sunlight (Shade through upper canopy all day), Full sun (6 or more hours of direct sunlight a day), Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil: High Organic Matter. Drainage: Moist, Occasionally Wet. Height: 4 ft. 0 in. - 5 ft. 0 in.. Spread: 1 ft. 0 in. - 2 ft. 0 in.. Spacing: 12 inches-3 feet, 3 feet-6 feet. Maintenance: Low. Propagation: Division, Seed. Regions: Coastal, Mountains, Piedmont.

Harvesting

Displays from August to November

Color: Brown/Copper. Type: Capsule. Length: < 1 inch. Width: < 1 inch.

Harvest time: Fall

Storage & Preservation

Cardinal Flower blooms are best enjoyed fresh and don't require cold storage—keep cut flowers in a cool room (65-70°F) in a vase with fresh water, changing water every 2-3 days. Cut flowers last 7-10 days. Since this is an ornamental wildflower, preservation focuses on extending bloom display and seed saving. Dry seed pods in paper bags at room temperature for winter storage and spring planting. Press individual blooms between parchment paper for botanical crafts. For long-term seed preservation, store dried seeds in cool, dry conditions (40-50°F, low humidity) in sealed containers for 2-3 years.

History & Origin

Native to eastern North America from Nova Scotia to Florida, Lobelia cardinalis has been cultivated in gardens for centuries, valued by indigenous peoples and early colonists alike for its striking beauty and ecological importance. The species itself represents the culmination of natural selection in moist woodland and wetland habitats rather than deliberate breeding; no specific breeder or cultivar development is documented. Its common name "Cardinal Flower" derives from the vibrant red plumage of the Northern Cardinal, reflecting how early American gardeners recognized the flower's similarity to this iconic native bird. The plant entered European horticulture in the 18th century and has remained a garden staple since, appreciated as an authentic native wildflower rather than a modern hybrid selection.

Origin: Eastern United States

Advantages

+Attracts: Butterflies, Hummingbirds, Pollinators
+Low maintenance

Considerations

-Toxic (Flowers, Fruits, Leaves, Roots, Sap/Juice, Seeds, Stems): Medium severity

Companion Plants

Wild Columbine and Monarda are the strongest pairings — both share Cardinal Flower's preference for consistently moist, slightly acidic soil (pH 6.0–6.5) and bloom in overlapping windows that string together a hummingbird and long-tongued bee corridor from late spring into summer. Astilbe, Hosta, and Ferns fill the understory without crowding the root zone, since Cardinal Flower roots stay relatively shallow. Skip Black Walnut entirely — juglone, the allelopathic compound walnut roots and leaf litter release, is broad-spectrum enough to kill Cardinal Flower outright. Lavender and Rosemary fail for a different reason: both need dry, alkaline conditions, and the steady moisture Cardinal Flower requires will rot them out within a season.

Plant Together

Wild Ginger

Provides ground cover and retains moisture in the shared shade habitat

Astilbe

Similar moisture and partial shade requirements, creates layered woodland garden

Hosta

Complementary foliage provides backdrop while sharing moist soil preferences

Ferns

Natural woodland companions that help maintain soil moisture and humidity

Wild Columbine

Both attract hummingbirds and thrive in similar moist, partially shaded conditions

Monarda

Fellow native that attracts beneficial insects and shares similar growing conditions

Heuchera

Provides contrasting foliage texture while tolerating same moist, shaded environment

Impatiens

Shares preference for moist soil and partial shade, extends blooming season

Keep Apart

Black Walnut

Produces juglone which is toxic to many plants including Cardinal Flower

Lavender

Requires dry, well-drained soil opposite to Cardinal Flower's moist soil needs

Rosemary

Needs dry Mediterranean conditions that conflict with Cardinal Flower's moisture requirements

Pests & Disease Resistance

Resistance

Generally healthy, may get leaf spot in very wet conditions

Common Pests

Slugs, snails, aphids

Diseases

Crown rot if soil drainage is poor, leaf spot

Troubleshooting Cardinal Flower

What you'll see, why it happens, and what to do about it.

Stems collapsing at soil level, crown turning brown and mushy

Likely Causes

Crown rot — typically Phytophthora or Pythium species thriving in waterlogged soil
Planting too deep, burying the crown below the soil surface

What to Do

1.Dig the plant, cut away rotted tissue, and replant in a spot with better drainage — raised beds work well
2.Amend heavy clay with coarse sand or perlite before replanting; target a soil pH of 6.0–7.0 and never let water pool for more than an hour after rain
3.Keep mulch at least 2 inches back from the crown — direct contact holds moisture right where rot starts

Ragged holes chewed in lower leaves and new growth, often worse after cool, wet nights

Likely Causes

Slugs or snails — they feed at night and hide under debris or mulch during the day
Aphid colonies clustering on tender stem tips, causing distorted new leaves

What to Do

1.For slugs, scatter iron phosphate bait (Sluggo is a common brand) around the base at dusk — reapply after heavy rain
2.For aphids, knock them off with a strong spray of water on two or three consecutive mornings, or apply insecticidal soap directly to the colony
3.Pull back mulch a few inches from the stems to reduce slug harborage

Frequently Asked Questions

Is Cardinal Flower good for beginner gardeners?▼

Yes! Cardinal Flower is rated Easy and thrives with minimal care once established. It naturally prefers moist soils, so it's forgiving if you forget to water occasionally. The main requirement is providing the right moisture level—not drought-tolerant, but well-draining rich soil prevents issues. Its hummingbird-attracting blooms and vibrant color make it rewarding for new gardeners.

When should I plant Cardinal Flower?▼

Plant Cardinal Flower in spring (after last frost) or early fall. Spring planting gives plants time to establish strong roots before summer. Fall planting works well in regions with mild winters. Seeds can be sown indoors 6-8 weeks before last frost or direct sown in moist soil. Seedlings prefer consistent moisture their first season before becoming established.

Can I grow Cardinal Flower in containers?▼

Yes, Cardinal Flower grows well in containers with consistently moist, rich soil. Use pots at least 12 inches deep with drainage holes, but keep soil evenly moist—don't let it dry out. Container plants may need more frequent watering than garden plants. Place in partial shade in hot climates to prevent soil from drying too quickly and keep blooms vibrant.

How long do Cardinal Flower blooms last?▼

Blooms typically last 4-6 weeks during peak season (mid-summer to early fall). Individual flowers open sequentially along the spike, extending the display period. Plant blooms in full sun to partial shade (4-6+ hours) for longest flowering. Deadheading spent flowers can encourage more blooms, though plants will self-seed if you leave some flowers to mature.

Will Cardinal Flower attract hummingbirds?▼

Absolutely! Cardinal Flower is famous as a hummingbird magnet. Its intense scarlet tubular flowers are perfectly designed for ruby-throated hummingbirds' long beaks and high-energy needs. The bright red color and abundant nectar make it irresistible to hummingbirds. Planting it near other nectar flowers extends hummingbird visits throughout the season.

What pests should I watch for on Cardinal Flower?▼

Main pests include slugs and snails, which eat foliage—use organic slug control or hand-pick. Aphids occasionally cluster on new growth; spray with water or insecticidal soap if needed. The good news: Cardinal Flower's moisture-loving habitat naturally limits many pests. Healthy plants in proper conditions rarely experience serious pest problems.