Plant type: Herbaceous perennial
Botanical name: Iris cristata
Hardiness: USDA Zones 3 to 8
A dwarf iris valued for its petite size and flowering in shade. Its flower has six petals; the three upright petals are called standards, and the three hanging petals are called falls. A characteristic golden yellow or white crest comes out of each fall; this is where the crested iris gets its name. Flowers are typically blue, lavender or white in color. Blooms in early spring. Foliage is narrow, green and swordlike, growing together in a fan shape. Leaves bend and droop slightly at the tips. Spreads freely by underground rhizomes. Plant size is three to nine inches tall and about 12 to 15 inches wide.
How to use it: Plant in mass for full effect. Use in the front of a mixed perennial border. Plant in a rock garden or let naturalize in a woodland garden. Combine with other spring-flowering shade perennials, like Virginia bluebells (Mertensia virginica) or wood poppy (Stylophorum diphyllum).
Culture: Prefers a rich, moist, well-drained soil; amend if necessary. Plant in full sun to partial shade (ideal). Tolerates deep shade. If planted in a sunny area, provide extra moisture to plants. Benefits by fertilization. To plant rhizomes, dig a shallow hole just below the soil surface. Place rhizomes with the growing tip pointed up and roots pointed down. Make sure the growing tip is oriented in the direction where you want it to go since the fan will grow from that point. If planting several rhizomes, space approximately one foot apart. Primarily propagated through division. Requires division every three to five years and can be done after it has finished flowering or in fall. To divide crested iris, cut back fans by at least half and lift the clump out of the ground. Hose off excess soil at the roots. With a clean, sharp knife, cut rhizomes apart into sections so that each section has one fan and some healthy roots. May have problems with slugs or snails chewing on foliage.
Special notes: The name iris is derived from Greek mythology where Iris was the goddess of the rainbow, therefore aptly named for its variety of flower colors. Crested iris have rhizomes which are thick, fleshy stems that grow underground.
- 'Alba'. Has white flowers.