Overview
Iris tuberosa is a bushy alpine rockery in the genus Iris, part of the Iridaceae family, with deciduous foliage. It typically grows around 0.1-0.5 metres tall and 0.1-0.5 metres wide, reaching full size in around 2-5 years. Iris tuberosa grows best in full sun, and tolerates most soils and alkaline and neutral pH. Its UK hardiness is rated H6. It is low maintenance. Suggested uses include cottage and informal garden, wildflower meadow and wildlife gardens.
About
Iris tuberosa, commonly known as snake's head iris or black widow, is a bushy herbaceous perennial from the Iris genus. It typically grows to a height and spread of 0.1 to 0.5 metres, reaching full size within 2 to 5 years. This deciduous plant thrives in full sun with a south-facing, sheltered aspect and prefers well-drained alkaline or neutral soils such as chalk, loam, or sand. Suitable for alpine rockeries, it offers year-round interest through spring, summer, autumn, and winter, and requires low maintenance.
About the genus
Iris takes its name from the Greek goddess of the rainbow, and for once the naming feels entirely earned. I can't think of another genus that covers so much ground — inky purples, burnt apricots, clean whites, blues that seem lit from inside — or so many situations. There are bearded irises that want their rhizomes baked in full sun, Siberian types happy in ordinary border soil, and species that will sit contentedly at the edge of a pond. What they share is the flower: three petals standing up, three falling away, built with a kind of architectural confidence most plants never attempt. Even out of bloom the foliage earns its place — those upright fans of blue-green leaves hold a border together for months. I grow them for the fortnight in May and June when nothing else in the garden can compete, and I've made my peace with that. Some plants are for the long haul. An iris is an event.
Written by Henry
Growing conditions
Best soil and position for Iris
- Sunlight
- Full sun
- Soil type
- Chalk, Loam, Sand
- Soil pH
- Alkaline, Neutral
- Soil moisture
- Well-drained
- Aspect
- South-facing
- Exposure
- Sheltered
- UK hardiness
- H6
Plant details
Iris tuberosa size, habit and characteristics
- Plant type
- Alpine Rockery, Herbaceous Perennial
- Habit
- Bushy
- Foliage
- Deciduous
- Height
- 0.1-0.5 metres
- Spread
- 0.1-0.5 metres
- Time to full height
- 2-5 years
- Suggested uses
- Cottage and informal garden, Wildflower meadow, Wildlife gardens
Care notes
Pruning and caring for Iris tuberosa
- Propagation
- Division of rhizomes from midsummer to early autumn
- Pest resistance
- Slugs, Snails, Thrips
- Disease resistance
- Aphid-borne viruses, Bacterial soft rot, Grey moulds
Frequently asked questions
Where is the best place to plant Iris tuberosa?
Iris tuberosa prefers full sun. It suits sheltered positions.
What soil does Iris tuberosa need?
Iris tuberosa is adaptable and grows happily in most soil types, including chalk, loam and sand. It prefers alkaline and neutral soil. Aim for soil that stays well-drained.
How big does Iris tuberosa grow?
Iris tuberosa reaches a height of 0.1-0.5 metres and a spread of 0.1-0.5 metres. It takes around 2-5 years to reach full size.
Is Iris tuberosa hardy in the UK?
Iris tuberosa has an RHS hardiness rating of H6, meaning it is very hardy, tolerating -20 to -15°C across most of the UK.
How do I propagate Iris tuberosa?
Division of rhizomes from midsummer to early autumn.
More in the Iris genus
- Iris 'Antigone' (TB)
- Iris 'Dauntless' (TB)
- Iris 'Dipped in Dots' (TB)
- Iris 'Ablaze' (MDB)
- Iris 'After the Storm' (TB)
- Iris 'Aldo Ratti' (TB)
- Iris 'Alene's New Love' (SDB)iris 'Alene's New Love'
- Iris 'Alpine Lake' (MDB)
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