Bearded iris, or Iris Germanica, are stunning, early-summer blooming flowers available in tones from white and pastels to jewel tones and near-black. After blooming, their long, pointed, upward-growing leaves form a distinct textural backdrop for a variety of summer perennials and annuals. Irises need to be planted, divided and replanted at the appropriate time to ensure adequate root development overwinter and support the following year's beautiful blooms.
Planting Bare-Root Rhizomes
The largest variety of bearded iris cultivars is available through mail-order nurseries which generally ship bare-root rhizomes. These bare-root rhizomes are usually shipped early to mid-summer. It is important to get bearded iris rhizomes planted early enough in the season to allow them to generate sufficient root stock to guard against being heaved out of the ground by winter frost and freezes, as well as to ensure strong early growth to support the following summer's blooms. Plant bare-root rhizomes 6 to 8 weeks before average first frost date for the planting location.
Garden centers offer potted iris plants, often well into their season's growth, in spring. Although this is early for planting bare-root iris, get potted iris plants into the ground as soon as possible. Be gentle with the potted, growing roots, which include hairlike tendrils more fragile than the heavier roots on bare-rooted rhizomes arriving later in the season. Don't allow the potted bearded iris roots to dry out; plant the rhizome at ground level, cover the descending roots with damp soil and water them in. A cool spring evening when dew will be falling through the night is an ideal time to plant potted bearded iris.
Dividing and Replanting
Bearded iris are best divided and replanted just after blooming, in early to mid-summer about the same time that new bare-root rhizomes would be planted. In a large iris collection, it is helpful to mark the foliage of blooming irises with an indication of their color so that division and replanting can proceed with some semblance of aesthetic order. Divide irises for replanting after a thorough watering, preferably in cool late afternoon or evening hours, to ensure that the roots and rhizome do not dry out.