About
Iris delavayi, the Delavay iris, is a vigorous, clump-forming rhizomatous perennial to 1.5 m with narrow leaves and branched stems bearing dark purplish-blue flowers to 8 cm across, each fall with a large white patch and yellow haft. A bold and spectacular iris for a moist, partly shaded border.
About the genus
Iris, the irises, are rhizomatous or bulbous perennials producing narrow, often sword-shaped leaves and distinctive flowers with three large, spreading or pendent fall petals alternating with three erect standard petals. They flower from late winter to early summer in every colour of the rainbow.
Growing conditions
SunlightFull sun, Partial shade
Soil typeClay, Loam, Sand
Soil pHAcid, Alkaline, Neutral
Soil moistureMoist but well-drained
AspectSouth-facing, East-facing, West-facing
ExposureExposed, Sheltered
UK hardinessH6
Plant details
Plant typeHerbaceous Perennial
HabitColumnar upright
FoliageDeciduous
Height1-1.5 metres
Spread0.1-0.5 metres
Time to full height2-5 years
Suggested usesCity and courtyard gardens, Coastal, Cottage and informal garden
Native toW China
ToxicityHarmful if eaten. Wear gloves and other protective equipment when handling. Pets: Harmful if eaten. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Care notes
CultivationGrow in any good garden soil that is preferably moist but not waterlogged. In drier soils, dig in well-rotted organic matter before planting then apply as a mulch each spring
PruningRemove any dying foliage in autumn, old flower stems can be cut down after flowering
PropagationPropagate by seed sown in autumn or by division in early autumn
Pest resistanceMay be susceptible to slugs, snails and thrips
Disease resistanceMay be susceptible to aphid-borne viruses, bacterial soft rot and grey moulds; see Iris diseases