The Siberian iris, Iris Sibirica, has to be one of the most accommodating perennials we can grow. From late May, through June, and sometimes beyond in some varieties, typical fleur-de-lis flowers sit on slender stalks, dancing above a sheaf of narrow foliage 90cm-1.2m (3-4 ft) tall.
Flowers of the wild species are mid-blue, but the base of the petals are jazzily marked and blotched in golden tones marked with dark blue or dark lines. They make good cut flowers, especially when paired with early roses. Sited in damp meadows or waterside, it really luxuriates and reaches its full potential. It'll also tolerate wet soil, as long as its rootstock isn't permanently submerged in water, and will also naturalise in damp grassland. Iris Sibirica can be grown in ordinary border soil, as long as it's not too acid or chalky, where it does best in semi-shade rather than full sun.
A range of new varieties have appeared in recent years, with colour breaks in pink and yellow, with bi-coloured and picoteed lower petals. Easy to grow, once established it forms a slowly-expanding clump of slender rhizomes. All you need to do is cut down the dead foliage in late winter. Old clumps can be resized or rejuvanated by lifting and dividing the clump every three to four years, but will take time to settle down again and flower to their full potential.