Water Iris

Height: 45-120cm (1”’j-4ft)

Water depth: 2.5-30cm (1-12in)

Features: flowers spring to summer

Soil: deep, lime-free, moist

Site: sun

Type: marginal

There are Four species, and many varieties, or iris for waterside use: Iris ensata, I. variegata. Pseudacorus and I. versicolor. All have dramatic, upright, sword-shaped leaves and attractive flowers in late spring to early summer.

Popular species and varieties:

Iris ensata (syn. I. kaempferi) (Japanese clematis iris) grows 60-75cm (2-2 1/2ft) tall, it prefers damp soil or very shallow water, 2.5-5cm ( 1-2in) deep. Its large flowers come in mauve, white, purple and blue.

‘Variegatus’ has green and cream striped foliage and purple flowers. Iris laevigata (Japanese water iris) grows best in a water depth of up to 15cm (6in). It has smooth, pale green leaves reaching 45-60cm. In early summer, three deep royal blue flowers open at the end of each stem. Varieties include ‘Atropurpurca’ (purple flowers), ‘Rose Queen’ (rose-pink), ‘Snowdrift’ (white and yellow) and ‘Variegata’ (blue (lowers, silverstriped leaves).

Iris pseudacorus (yellow flag or yellow water iris) grows in up to 30cm (1 ft) of water. Reaching 90-120cm (3-4ft), it has blue-green, ridged leaves. The branching stems carry five or more yellow flowers sometimes marked with brown veins, in late spring and early summer.

Varieties include ‘Golden Queen’ (golden flowers), ‘Sulphur Queen (primrose-yellow) and ‘Variegata’ (gold variegated spring leaves). Iris versicolor (American blue flag) grows to 45cm and produces distinctive, plum-coloured blooms with yellow markings. It thrives in 5-10cm (2-4in) of water. A popular variety is ‘Kermesina’, with wine-red flowers flecked with white.


Plant along the margins of ponds or streams in good, deep, moist, lime-free soil in early to mid spring. Divide and replant clumps every three years.

Propagation: Divide the rhizomes after flowering. Replant immediately.

Pests and diseases: Trouble free.

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