Iris versicolor 'Gerald Darby' - Blue Flag Iris, Pond Marginal Plant

Iris 'Gerald Darby' (listed by the RHS as Iris × robusta 'Gerald Darby', and often sold as Iris versicolor 'Gerald Darby') is a tall, hardy iris with narrow, arching leaves. In spring the flower stems and leaf bases are flushed purple, and in June and July it carries violet-blue flowers with a yellow flash and dark veins.

Gerald Darby at a glance

Botanical name	Iris × robusta 'Gerald Darby' (syn. Iris versicolor 'Gerald Darby')
Common name	Blue flag iris 'Gerald Darby'
Plant type	Clump-forming iris; mostly dies back in autumn
Height and spread	About 90 cm–1.2 m tall in flower
Flowers	Violet-blue with a yellow flash and dark veins, June and July
Position	Full sun or part shade
Soil	Moist to wet, deep, humus-rich soil
Pond depth	Wet soil or up to 10–15 cm of water
Hardiness	RHS H7 – very hardy (below -20°C)
Native to	Hybrid iris (not UK native)

Where to plant Gerald Darby

A pond shelf with up to 10–15 cm of water
Wet soil at the margins of ponds and streams
Bog gardens with deep, rich soil

Is it good for wildlife?

The upright stems help aquatic wildlife climb out of the pond. One parent, Iris versicolor, has escaped into British wetlands, so keep it to garden ponds.

How to plant and care for it

Plant from spring to late summer. Watch for slugs, snails and thrips.

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 come in 7 cm, 9 cm, 1 litre and 3 litre bare-root sizes and cost less per plant. The 2x Pot & Compost option is two plants supplied with pots and compost.