Do they need lots of water?

They prefer consistently moist soil but do not need to be submerged like water irises.

When should I divide them?

Divide them in early autumn or early spring when the plant is not actively blooming.

Plant guide

Siberian iris.

Iris sibirica

Pronounced EYE-ris sy-BEER-ih-kuh

Also known as German Iris, Siberian Iris, Sibirian Flag, Turkish Iris

The Siberian iris is a hardy perennial that brings elegant, grass-like foliage and delicate blooms to your garden. It thrives in moist, well-draining soil and is quite adaptable to various climates. You will love how these plants add vertical interest to your flower beds.

Another photo of Siberian iris — Photo by Татьяна Максимова (CC BY) via iNaturalist

At a glance

Care level: Easy
Plant type: Perennial
Light: Full sun to partial shade
Indoor light: Bright indirect
Water: Every 3 to 7 days
Mature size: 2 to 4 feet
Growth rate: Medium
Hardiness: USDA 3 to 9
Bloom time: Late spring to early summer

Care

Keep the soil consistently moist, especially during the growing season. Watch for yellowing leaves which may indicate poor drainage or nutrient issues. Deadhead spent flowers to keep the plant looking tidy and encourage potential repeat blooms.

Watering: Keep the soil evenly moist but not waterlogged.
Feeding: Apply a balanced fertilizer once in early spring as new growth appears.
Pruning: Cut back the foliage to the ground in late autumn after the first frost.
Repotting: Divide the clumps every few years to maintain vigor and prevent overcrowding.
Soil: Moist, fertile, slightly acidic soil
Soil pH: 5.5 to 7.0
Temperature: -35 to 30°C
Humidity: 40 to 70%
Drought tolerance: Low
Lifespan: Perennial, typically 10 plus years
Deer and rabbits: High

Signs it needs repotting

Roots growing out of drainage holes
Water running straight through the pot
Reduced flowering

Safety

People: The rhizomes and leaves contain irisin, which can cause skin irritation and stomach upset if eaten.
Pets: This plant is considered toxic to cats and dogs if ingested.
Children: Keep children away from the rhizomes as they are toxic if ingested.
Contact allergens: Handling the foliage may cause mild skin irritation in sensitive individuals.
Airborne allergens: The pollen is generally not considered a significant airborne allergen.
Edibility: This plant is not intended for consumption and can cause digestive distress if ingested.

How to identify it

Slender, grass-like green foliage
Beardless flowers with three petals
Sturdy, upright flower stalks
Deep blue to violet blooms
Clump-forming growth habit

Height: 0.6 to 1m
Spread: 0.45 to 0.6m
Leaves: green, deciduous
Flowers: blue, violet, white, yellow, 5 to 8cm
Fruit: brown, late summer

Problems to watch for

Iris BorerCommon
Leaf SpotCommon
Root RotUncommon
Slugs and SnailsUncommon
Soft RotUncommon
AphidsRare

By symptom

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Growing it

Propagation: division, seed
When to plant: spring, autumn
Overwintering: Cut back the foliage to the ground in late autumn after it has turned brown. No special protection is needed as they are very cold hardy.
In containers: They grow well in large containers, provided you keep the soil consistently moist.

Division

1. Dig up the clump in early autumn.
2. Use a sharp spade or knife to cut the rhizomes into sections.
3. Ensure each section has healthy roots and foliage.
4. Replant immediately at the same depth as before.

Pair these with moisture loving perennials to create a lush, low maintenance garden bed.

Grows well with

Daylily — They share similar moisture needs and provide a nice contrast in leaf texture.
Lady's Mantle — The soft, scalloped leaves of lady's mantle look lovely against the upright, grass like iris foliage.

Similar species

Bearded Iris — Both are popular garden irises but have different soil and moisture requirements.

Science

Family: Iridaceae
Genus: Iris
Order: Asparagales
Class: Liliopsida
Native range: Central and Eastern Europe to Central Asia.
Conservation: This species is not currently of conservation concern.

It thrives in damp meadows and along stream banks where it can access reliable moisture throughout the growing season.

Value to wildlife: nectar source
Pollinators: bees, butterflies, hummingbirds
Uses: border planting, rain gardens, cut flowers, mass planting

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Light: 7/9
Nutrients: 5/9
Salinity: 2/9
Soil reaction: 5/9
Temperature: 4/9
Moisture: 7/9

Taxonomy resolved against GBIF.

Questions people ask

Do they need lots of water?: They prefer consistently moist soil but do not need to be submerged like water irises.
When should I divide them?: Divide them in early autumn or early spring when the plant is not actively blooming.

Where the name comes from

The genus name honors Iris, the Greek goddess of the rainbow, while the specific epithet sibirica refers to the region where it was once thought to originate.

Good to know

Despite the name, they are native to central and eastern Europe rather than Siberia.
They are much more resistant to iris borer than bearded irises.
The flowers are held well above the foliage on slender, wiry stems.

Also in

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This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.