Iris (beardless sibirica)
Height 60-110cm (2 – 3-3/4ft)
Planting distance 45-60cm (18-24in)
Flowers in early summer
Good moisture retentive
Sun or partial shade
Rhizomes available late spring to early summer
The species and hybrids in this section of the rhizomatous beardless iris group are hardy and easy to cultivate, provided the soil is moisture retentive. Grow them in herbaceous borders for garden decoration and cutting, or along the edges of garden pools. A sunny site is preferable but these summer-flowering irises will tolerate partial shade.
Popular species and hybrids Iris sibirica hasin varying shades of blue with white veins on the falls. It stands 60-110cm (2 – 3-1/2ft) high and has a well-branched stem. Plant the rhizomes 60cm (24in) apart. Hybrids come in shades of blue, or white, and have larger flowers. The plants reach 90cm (3ft) high and have a less branching habit. Set the rhizomes 45-60cm (18-24in) apart.
Plant from mid summer to autumn or in, in good moist soil in a sunny or partially shaded site. Set 2.5cm (1in) deep in groups. If growing them near water, make sure the rhizomes are at least 15cm (6in) above water level. Avoid hoeing or cultivating around plants.
Divide large clumps every five years into four to eight pieces. Replant 2.5cm (1in) deep, after flowering, in autumn, or in spring when growth restarts.
Iris (miscellaneous beardless) iris
Height 23-75cm (9-30in)
Planting distance 30-45cm (12-18in)
Flowers early summer; mid autumn to mid spring
Moist humus-rich or well-drained soil
Shady or sunny site
Rhizomes available in spring
Some of the beardless rhizomatous irises have a character or uniqueness of their own which makes them well worth considering.
Popular species Iris foetidissima, called stinking iris, gladdon or gladwyn iris, is renowned for its seed pods which split open and peel back to reveal striking scarlet seeds in autumn. These are far more attractive than the insignificant pale purple flowers that appear in early summer. They can be dried and used in winter arrangements. The plants stand 75cm (30in) high and give off a rank smell when bruised. Several forms are available: I. foetidissima lutea has yellow flowers with brown veining and orange red seeds, and ‘Variegata’ has attractive variegated leaves. Iris unguicularis (syn. I. Stylosa), sometimes called the Algerian iris, is a winter-flowering species with soft lavender or lilac flowers marked by a yellow blaze on the falls. Flowering begins in mid autumn and continues until mid spring. The plants are 23cm (9in) high with dark green, evergreen foliage.
Plant I. Foetidissima rhizomes in summer in moist humus-rich soil. Set the rhizomes 30-45cm (12-18in) apart in clumps and 3cm (1-1/2in) deep. This species does well in shade.
Plant I. Unguicularis rhizomes in summer, 38cm (15in) apart and 2.5cm (1in) deep, in small clumps. The site must be sunny, with well-drained even poor soil.
Divide and replant the rhizomes in early and mid autumn.