Common Name: Siberian iris
Type: Herbaceous perennial
Zone: 3 to 8
Height: 3.00 to 4.00 feet
Spread: 2.50 to 3.00 feet
Bloom Time: May
Bloom Description: Deep purple
Sun: Full sun to part shade
Water: Medium to wet
Suggested Use: Rain Garden
Tolerate: Rabbit, Deer, Drought, Erosion, Clay Soil, Wet Soil
Easily grown in moist, fertile, humusy, organically rich, neutral to slightly acidic, medium moisture, well-drained soils in full sun to part shade. Siberian iris is an adaptable plant which tolerates a wide range of soils, including boggy ones, but will generally perform well in average garden soils. Avoid soils that are too wet or too dry. In too much shade, plants tend to produce fewer flowers and foliage tends to flop. Best with consistent moisture from the onset of spring growth until several weeks after the flowers fade. Continue irrigation after bloom, however, to keep foliage clumps attractive. Rhizomes should be planted 1-2” below the soil surface and 1-2’ apart. In cold winter regions, plant the rhizomes in early spring or late summer. In mild winter regions, plant the rhizomes in fall. Divide plants as needed when overcrowding occurs and decreased flowering is evident. Remove flowering stems promptly after bloom unless the seed pods are considered to be an attractive addition to the garden.
Plants in the Siberian iris group are chiefly of hybrid origin, primarily being derived from two blue-flowered Asian species, namely, I. sibirica (central Europe to northeastern Turkey and southeastern Russia) and I. sanguinea (Russia, Korea and Japan). Arching, narrow, grass-like, linear, blue-green leaves form a vase-shaped foliage clump to 2’ tall. Flowering stems rise above the foliage to 3’ tall in May-June, each stem bearing 2-5 flowers in colors which primarily include blue, lavender, purple and white, but sometimes yellow, pink and wine. Each flower features upright standards and flaring to drooping falls. In comparison to bearded varieties, Siberian irises have smaller beardless flowers, narrower grass-like leaves and an absence of thick fleshy rhizomes. After bloom, the foliage clump will retain its blue-green color into the fall, often displaying showy leaves reminiscent of some ornamental grasses.
Genus named for the Greek goddess of the rainbow.
'Caesar's Brother' produces deep purple flowers in late spring on rigid stems which rise to 40" high above a clump of arching, narrow, grass-like, linear leaves. Morgan Award winner (1953).
Siberian irises are generally pest-free, with very little susceptibility to the two main problems of bearded iris, namely iris borer and bacterial soft rot.
Mixes well with other perennials in borders. Also effective when planted along a slope or hillside, along a path or along a stream or pond margin. A good moisture-loving plant for moist garden areas. Massed plantings and well-placed specimens can enhance almost any setting, and the foliage provides lasting beauty after bloom. Excellent cut flower, but usually lasts only two days.