2 named cultivars

perennial

Yellow Flag Iris

Iris pseudacorus

The Story

Plant Bio

Iris pseudacorus is a vigorous, spreading, beardless iris that thrives in wet, boggy conditions. It is considered highly invasive in many parts of North America.

Features bright yellow flowers in late spring and sword-like, gray-green leaves. Its ability to grow in standing water makes it suitable for water margins and bog gardens, but its invasive nature requires careful consideration.

Uses & Benefits:

Bright yellow flowers and lush foliage make this plant a striking pondside feature.

Acts as a natural water filter and erosion control.

Supports pollinators like bees and butterflies.

Essentials

At a Glance

Plant Type

Perennial

Height

48"

Width

24"

Light

Full Sun, Partial Sun

Zones

4, 5, 6, 7, 8, 9

Water

Requires consistently moist soil

Humidity

Prefers moderate to high humidity

Lifespan

Perennial

Native To

Europe, North Africa, West Asia

Toxicity

All parts are toxic if ingested

Planting

How to Grow

Tuck rhizomes into moist, well-draining soil in spring.
Mist cuttings with water weekly to encourage rooting.
Plant in full sun for optimal growth.
Water regularly to keep soil moist but not waterlogged.
Fertilize with a balanced fertilizer in early spring.
Divide clumps every 3-4 years to maintain vigor.

Pro Tip

Plant near water for best growth and vibrant blooms.

Keep It Thriving

Care Guide

Do

Provide consistent moisture 🌱
Ensure full sun exposure
Divide every few years to prevent overcrowding

Don't

Avoid waterlogging soil ❌
Don’t neglect pruning dead leaves
Skip fertilizing in late fall

Seasonal Care Calendar

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

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Pondside borderTall, yellow-flowered accentWildflower meadow edge

Companion Plants

Caltha palustris Lobelia cardinalis Carex spp.Marsh Marigold Pickerelweed

Multiply

Propagation Methods

Good to Know

Common Questions

Yellow Flag Iris questions

What zones can Yellow Flag Iris grow in?

Yellow Flag Iris is hardy in USDA Zones 4–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Yellow Flag Iris deer resistant?

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

When does Yellow Flag Iris bloom?

Yellow Flag Iris typically blooms in late spring through early summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Yellow Flag Iris need full sun?

Yellow Flag Iris does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.