Stinking iris

Sun

Partial shade or full shade; tolerates sun where the soil does not become excessively dry.

Water

Water regularly while establishing. Established clumps tolerate dry shade, but benefit from occasional deep watering during prolonged drought.

Soil

Well-drained soil, including clay, loam and chalk; tolerates a broad pH range. Avoid persistently waterlogged ground.

Height

1.5-3 ft (0.45-0.9 m)

Spread

1-2 ft (0.3-0.6 m)

Flowers

Late spring to early summer; small, dull lilac-grey flowers, often with yellow-brown markings.

Foliage

Evergreen. Upright, leathery, dark green, sword-shaped leaves with an unpleasant smell when crushed. Leaves may become damaged or die back in severe winters.

Growth

Slow to moderate; gradually forms clumps and may self-seed.

Care needed

Low

• Pollinators
• Deer resistant
• Drought tolerant
• Heat tolerant
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.3 ft (0.4 m)

3. After 2 years

   1.6 ft (0.49 m)

4. After 3 years

   1.9 ft (0.59 m)

5. After 5 years

   2.2 ft (0.68 m)

   full size

About 4 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

the UK

Invasive in

Australia

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Slow

• Water newly planted clumps through their first growing season, allowing the surface soil to dry between waterings.
• Apply a light mulch of leaf mould or compost in spring, keeping it away from the crown.
• Avoid heavy feeding; a modest annual compost dressing is usually sufficient.
• Divide overcrowded clumps in spring and replant promptly at their original depth.
• Remove seedpods before they open if seedlings or spread into nearby natural areas would be a problem.

Pruning. Cut damaged or dead leaves back to the base in late winter or early spring; do not shear healthy foliage. Leave flower stems for autumn seed display, or cut them down before the pods open to limit self-seeding.

Early spring

Remove winter-damaged leaves and check that the crown is not sitting in wet soil.

Spring

Plant or divide clumps, water well and add a light mulch.

Late spring

Leave fading flower stems in place if you want ornamental seedpods.

Summer

Water new plants during dry spells; established clumps usually need little attention.

Autumn

Enjoy the opening seedpods, or remove them before seeds scatter.

Winter

Pull out unwanted seedlings and leave healthy evergreen foliage intact.

• Plant beneath deciduous trees or tall shrubs for evergreen structure in dry shade.
• Combine with ferns and hellebores along a shaded path, using its upright leaves to contrast with softer foliage.
• Use small groups in woodland borders for orange-red autumn and winter seed displays.
• Plant against a shaded wall or fence where a durable foliage plant is needed.

Garden styles it suits: Woodland, Low-maintenance, Winter interest, Autumn colour, English country and Green on green.

Plant it with: Hellebores, Epimediums, Hart's-tongue fern, Soft shield fern, Hardy cyclamen and Bergenias.

Wildlife: Flowers provide some food for visiting insects, and birds can eat and disperse the seeds. Dense clumps offer shelter for small garden animals, but this is not a major nectar plant.

• Slugs and snails can damage young leaves: inspect during damp weather, remove by hand and use targeted controls if necessary.
• Leaf spots can mark older foliage: remove badly affected leaves, improve air circulation and avoid overhead watering.
• Rhizome or crown rot develops in waterlogged soil: improve drainage or move the plant, discarding soft, rotting tissue.
• Unwanted seedlings can spread beyond the clump: remove pods before they open and pull seedlings while small.

Toxic if eaten by people, cats, dogs and horses. All parts should be treated as harmful, particularly the rhizomes; keep the conspicuous seeds away from children and pets. Ingestion can cause mouth irritation, vomiting, abdominal pain and diarrhoea, and sap may irritate skin. Seek medical or veterinary advice after ingestion.

Where it spreads. Spreads by seed, including seed carried by birds. It is an environmental weed in parts of south-eastern Australia, including Victoria and Tasmania, and is invasive in New Zealand. It also escapes cultivation in coastal California. Check local guidance before planting near woodland or other natural areas.

• Yellow flag iris (Iris pseudacorus)

  Usually taller, with bright yellow flowers and a strong preference for wet ground. It lacks the conspicuous orange-red seed display of stinking iris.

• Bearded iris (Iris germanica)

  Has larger, showier flowers with a fuzzy beard on the lower petals, often grey-green leaves, and thick rhizomes visible at the soil surface.

• Siberian iris (Iris sibirica)

  Has narrower, grass-like leaves that die back in winter and usually blue-violet flowers. Its seedpods do not display bright orange-red seeds.

The Latin foetidissima means 'very foul-smelling', referring to the unpleasant smell released when the leaves are crushed.

Propagation. Divide established clumps in spring, retaining healthy roots and a fan of leaves on each division. Sow ripe seed in autumn in pots outdoors; germination can be slow and irregular, and seedlings take several years to flower.

Accepted botanical name

Iris foetidissima

In the US and Canada

Introduced in Canada and the lower 48 states.

Native range

Algeria, Azores, Baleares, Corse, France, Great Britain, Italy, Morocco, Portugal, Sardegna, Sicilia and Spain.

Measured

Soil pH 6.5 to 7. Average height 65 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.