perennial

Thunberg's Cobra Lily

Arisaema thunbergii

Essentials

At a Glance

Plant Type

Perennial

Height

18 inches

Width

10 inches

Light

Partial Sun, Shade

Zones

6, 7, 8, 9

Water

Moist but well-drained

Humidity

Moderate

Lifespan

Perennial

Native To

Japan, Korea

Toxicity

Yes

The Story

Plant Bio

Arisaema thunbergii is a perennial woodland plant distinguished by its striking, umbrella-like foliage and unique spathe and spadix flower structure, typically exhibiting green and purple hues. Characterized by a dark purple or greenish spathe and a remarkably long, thread-like spadix that extends from the flower, resembling a fishing line.

Bloom Period:

EarlyLate

Uses & Benefits:

Adds unique architectural form and deep purple color to shaded gardens.

Prefers moist, well-drained soils, enhancing garden soil quality.

Supports shade-loving insects and maintains soil moisture levels.

Planting

How to Grow

Tuck bulbs 2 inches deep in well-draining moist soil.
Water regularly to keep soil moist, especially in dry periods.
Mulch around plants to retain moisture and suppress weeds.
Place in partial to full shade for optimal growth.
Allow foliage to die back naturally after flowering.
Divide clumps every 3-4 years in early spring or fall.

Pro Tip

Ensure soil stays consistently moist and provide shade for best results.

Keep It Thriving

Care Guide

Do

Water regularly to keep soil moist 🌱
Apply mulch to conserve moisture
Plant in shaded areas

Don't

Avoid full sun which can scorch leaves ❌
Do not allow soil to dry out completely
Avoid heavy, waterlogged soil

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Divide
Fertilize
Mulch
Plant
Spring Cleanup

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Shaded woodland borderMoist shaded garden bed

Companion Plants

Ferns Hostas Astilbes Heucheras

Multiply

Propagation Methods

Good to Know

Common Questions

Thunberg's Cobra Lily questions

What zones can Thunberg's Cobra Lily grow in?

Thunberg's Cobra Lily is hardy in USDA Zones 6–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Thunberg's Cobra Lily deer resistant?

Yes — Thunberg's Cobra Lily is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.

When does Thunberg's Cobra Lily bloom?

Thunberg's Cobra Lily typically blooms in mid-spring through late spring. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Thunberg's Cobra Lily need full sun?

Thunberg's Cobra Lily does best in part shade.