Iris cristata

Common Names

Dwarf Crested Iris, Crested Iris, Lady's Calamus

Summary

Iris cristata, the dwarf crested iris, is a rhizomatous, low-growing perennial native to the eastern United States that forms dense colonies as a ground cover in woodland understories and shaded slopes. It typically reaches 4–9 inches tall and 6–12 inches wide, with pale blue to lavender or white blooms in spring bearing three upright standards, three falls featuring a central white patch and a gold crest, and three parallel crested ridges on the sepals; slender sword-shaped leaves persist after flowering, contributing to a green ground cover. In cultivation, it prefers partial to full shade with moist, humus-rich, well-drained soil; in sunnier locations soil must remain consistently moist. It is hardy in USDA zones 3–9 and propagates by division every 3–4 years, with rhizomes divided and replanted about 6 inches apart. Commonly grown as a ground cover or edging in shady rock gardens, woodland borders, and naturalized plantings, it also attracts pollinators such as bees and hummingbirds and is deer resistant; snails and slugs can be a problem in some situations.

Lifecycle

Perennial

Height

6-9 inches

Spread

6-12 inches

Hardiness Zones

Zones 3-9

Sunlight Requirements

Best in Full Sun to Partial Shade.

Soil Type

Well-drained, humus-rich loam soil, pH about 5.5 to 6.5

Soil Drainage

Well-drained soil

Soil pH

5.5-7.0 (slightly acidic to neutral)

Bloom Color

Blue, Purple, White

Bloom Time

Spring (April to May)

Foliage Color

Green (including yellow-green)

Fall Foliage Color

Green

Leaf Lifecycle

Deciduous

Growth Rate

Rapidly spreading

Seasons of Interest

Spring

Propagation Methods

Seeds, Division

Attracts Wildlife

Attracts bees, hummingbirds, and other pollinators