Iris versicolor - Blue Flag Iris, Pond Marginal Plant

Iris versicolor, known as blue flag iris, is a North American iris with narrow, upright leaves and branched stems of violet-blue flowers. Each flower is 6–8 cm across with white veining and a yellow patch at the base.

Blue flag iris at a glance

Botanical name	Iris versicolor
Common name	Blue flag iris
Plant type	Clump-forming iris; dies back in winter
Height and spread	About 60–80 cm tall, up to 50 cm wide
Flowers	Violet-blue, 6–8 cm across, veined white with yellow at the base, June to August
Position	Full sun or part shade
Soil	Moist to wet, acid to neutral soil
Pond depth	0–10 cm of water over the crown
Hardiness	RHS H7 – very hardy (below -20°C)
Native to	Eastern North America (not UK native)

Where to plant blue flag iris

A pond shelf with up to 10 cm of water over the crown
Bog gardens and wet borders that never dry out
Garden ponds, as a smaller alternative to yellow flag

How to plant and care for it

Plant from spring to summer and do not let it dry out. Divide crowded clumps from midsummer to early autumn.

Is blue flag iris invasive?

It is not native and has escaped into the wild in parts of Britain, so keep it in garden ponds and do not plant it into natural waters.

Is it poisonous?

Yes. Irises are harmful if eaten by people or pets, so wear gloves when handling it.

Which size should I buy?

Bare-root plants (7 cm, 9 cm, 1 litre and 3 litre) arrive without a pot or compost and are the most economical way to plant a group. Potted plants (9 cm, 1 litre and 3 litre) arrive growing in our peat-free compost and give a faster display. Packs of 3 cost less per plant. The 2x Pot & Compost option is two plants supplied with pots and compost.