Height 15-45cm (6-18in)
Planting distance 23-60cm (9-24in)
Flowers late spring to early summer
Neutral or acid
Sun or partial shade
Rhizomes available in autumn
This North American group of irises is also rhizomatous, but the species in the group have no beards – the falls are perfectly smooth. Their evergreen foliage is narrow, tough and dark green. All the species and hybrids are hardy and all flower in late spring to early summer and make good cut. They grow best in neutral to acid soils, making excellent companions for rhododendrons.
Popular species and hybrids Iris douglasiana usually has flowers in shades of blue-purple or lavender with veining on the falls. Each stem carries four or five blooms, 30-45cm (12-18in) above ground. Plant the rhizomes 60cm (24in) apart. Unlike other Pacific coast irises, this species tolerates lime.
Iris innominata usually has cream, buff, yellow or orange flowers with rich brown veins, though there are also orchid-pink and blue-purple forms. Each stem carries one flower or occasionally two, 15cm (6in) above ground, accompanied by grass-like ever- green leaves. Grown under favour-able conditions – humus-rich soil – it soon forms small clumps. Plant the rhizomes 23cm (9in) apart. Hybrids look like crosses between I. douglasiana and I. innominata. The flowers vary in colour from white through yellow and orange to pale blue and purple. They are free-flowering and reach between 23-45cm (9-18in) high. Plant 30cm (12in) apart.
Plant the rhizomes of species irises and hybrids in late autumn in sun or partial shade. I. Douglasiana tolerates lime; I. innominata and the hybrids prefer neutral or acid soil.
In early autumn, when new roots start to grow, divide and replant rhizomes. Water well – the soil must not be allowed to dry out.