About
Iris tenax, the tough-leaved iris, is a strong, hardy rhizomatous evergreen perennial to around 40 cm with narrow, green, strap-like foliage. Blue-purple flowers with central feathery white and yellow markings appear in late spring. A reliable and ornamental iris for a sunny, well-drained border.
About the genus
Iris are rhizomatous or bulbous perennials with narrow, often sword-shaped leaves and erect stems bearing flowers with three large, spreading or pendent fall petals alternating with three erect, often smaller, standard petals in late winter, spring or early summer. One of the most varied and spectacular of all plant genera, encompassing everything from tiny bulbous species to tall bearded border irises.
Growing conditions
SunlightFull sun, Partial shade
Soil typeChalk, Clay, Loam, Sand
Soil pHAcid, Alkaline, Neutral
Soil moistureMoist but well-drained, Well-drained
AspectEast-facing, South-facing, West-facing
ExposureExposed, Sheltered
UK hardinessH7
Plant details
Plant typeHerbaceous Perennial
HabitClump forming
FoliageEvergreen
Height0.1-0.5 metres
Spread0.1-0.5 metres
Time to full height2-5 years
Suggested usesCity and courtyard gardens, Coastal, Cottage and informal garden, Gravel garden, Patio and container plants, Rock garden, Wildflower meadow
Native toWest N America, Mexico
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 moist but not waterlogged but prefers drier conditions. Dislikes root disturbance during growing season
PruningRemove any dying foliage in autumn, old flower stems can be cut down after flowering
PropagationPropagate by division of rhizomes from midsummer to early autumn. See dividing irises
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