Iris tenax

Common Names

Oregon Iris, Toughleaf Iris

Summary

Iris tenax, Tough-leaved Iris or Oregon iris, is a perennial native to the Pacific Northwest, occurring in western Oregon and western Washington west of the Cascades with a subspecies extending into northwestern California. It is rhizomatous and forms dense clumps of narrow, grass-like light-green leaves and slender flower stalks that bear showy blooms in mid- to late spring; colors include purple and lavender-blue, with occasional white, pink, or yellow forms. Typical height is about 6–14 inches, and leaves stay green through the season. It tolerates drought once established and prefers moist to well-drained soils, often occupying open prairies, meadows, woodlands, or forest openings.

Cultivation notes: best in full sun to partial shade, with soils that are well-drained and not subject to standing water; drought tolerance develops after establishment. It propagates by seed and rhizomes, forms large clumps, and spreads slowly. It is deer and rabbit resistant and attractive to pollinators such as hummingbirds. Caution: all parts may be poisonous if ingested, and handling the foliage can cause skin irritation.

Lifecycle

Perennial

Height

8-14 inches

Spread

12-24 inches

Hardiness Zones

Zones 5b-10b

Sunlight Requirements

Ideally full sun to partial shade.

Soil Type

Well-drained soil, sandy or loamy texture, not clay, light to humus-rich soil, tolerates a moisture range from dry to moist

Soil Drainage

Well-drained soil, preferably sandy or loamy, with avoidance of clay and standing water.

Soil pH

6.0-8.0

Not a specific ideal; not particular about soil pH

Bloom Color

Purple, lavender, blue (lavender-blue), white, cream, yellow

Bloom Time

Spring to Summer

Foliage Color

Green

Fall Foliage Color

Green

Leaf Lifecycle

Deciduous

Growth Rate

Slow

Seasons of Interest

Spring, Summer, and Winter.

Propagation Methods

Seed propagation and division

Attracts Wildlife

Attracts hummingbirds, butterflies, and other pollinators