|Rhizomatous irises have rhizomes as rootstocks, close to or on the surface, or just below ground-level, which produce linear to sword-shaped leaves, nearly always in basal fans, and simple or branched flower stems. The flowers have 3 upright petals, called standards, and 3 large, pendent or spreading petals, called falls. Siberian irises lack the "beard" of colored hairs at the base of each fall that other iris groups have.
Irises in the Spuria group bloom from late spring to midsummer, and prefer a dry summer dormancy, alkaline soil, and high levels of fertility. Best planted from midsummer to early fall; apply shallow mulch in the spring. 'Blue Zephyr' is pale blue flowers.