The short answer

Quick Answer

Iris (Bearded and Siberian) thrives in full sun or partial shade or full shade on chalky, clay soils (pH 6-7.5), free-draining. Reaches 60cm to 1m tall in flower, slowly spreading. Excellent chalk tolerance. Hardy to around -25°C.

Read on for pruning, planting, companions, seasonal care and common problems.

On this page

Pruning

When: After flowering. Tidy leaves in autumn

How: Cut flower stems to ground level after bloom. Trim damaged leaves to a fan shape

Origin, history and folklore

Origin: Northern hemisphere, including the UK

Native or exotic: Native. Iris foetidissima is a true British native of chalk woodlands

History: Iris growing goes back to ancient Egypt. Modern bearded irises were bred from the 1840s onwards

Folklore: The fleur-de-lis, symbol of French royalty, is based on the yellow flag iris that grew along the River Lys

Fun fact: The iris is named after the Greek goddess of the rainbow, who carried messages between gods and mortals along a rainbow bridge

Historical medicinal uses: Iris rhizomes were used historically to make orris root for perfume. Some parts irritate skin

Wildlife and biodiversity

Pollinators: Bees. Bearded irises provide a landing platform on the falls [4][5]

Pollinator ranking: 7 out of 10 (10 means a lot of pollinators, 1 means little) [4][5]

Biodiversity value: 6 out of 10 Medium. Native iris supports several moth species[4][5][13]

Seasonal highlight: 7 out of 10 Flowers May to June. Some bearded irises repeat in September[3][4]

Companion planting and pests

Companion planting: Bearded irises pair with dianthus and hardy geraniums in sunny borders. Siberian irises suit astilbe and damp borders

Pest control: Watch for iris sawfly on Siberian irises in May

Common diseases and issues: Iris rhizome rot, leaf spot, iris scorch. See RHS Iris page

Invasive note: Not invasive. Bearded irises need dividing every 3 to 5 years to keep flowering

CGM care note

Bearded irises flower best when the rhizomes are baked in sun. We plant them shallowly so the top of the rhizome sits above soil, and we never mulch over them.

CGM guides mentioning Iris (Bearded and Siberian)

These articles from our Gardening Knowledge library mention Iris (Bearded and Siberian) and may be useful if you are researching or growing this plant.

Useful resources

Plant relationships, Iris (Bearded and Siberian)

How Iris (Bearded and Siberian) fits with other plants in a real Chiltern garden, what it works well with, what to avoid, and what to use instead in tricky spots.

Works well with

  • Agapanthus (African Lily), shares similar growing conditions, soil, light and drainage needs overlap
  • Bugle, shares similar growing conditions, soil, light and drainage needs overlap
  • Apple Tree, shares similar growing conditions, soil, light and drainage needs overlap
  • Aquilegia (Columbine), shares similar growing conditions, soil, light and drainage needs overlap
  • Astilbe, shares similar growing conditions, soil, light and drainage needs overlap
  • Bay, shares similar growing conditions, soil, light and drainage needs overlap

Avoid planting beside

Better choice for exposed sites

Better choice for shade

Replacement for failed box

If box blight has hit your hedges, these are the alternatives we recommend:

Seasonal succession partners

Plants with non-overlapping flowering windows to extend the season:

Relevant services

Related articles

Local projects using this plant

See our portfolio for real gardens where we've used Iris (Bearded and Siberian).

Chiltern growing year

12-month care calendar

Use this as a seasonal prompt for this plant. Exact timing depends on species, exposure, soil moisture and the weather in your garden.

JanuaryCheck winter damage and protect vulnerable new growth.
FebruaryPrune only where the plant and weather allow; plan spring work.
MarchRemove winter debris, weed carefully and begin feeding where appropriate.
AprilPlant in workable soil and water new plants during dry spells.
MayMulch before the ground dries and watch for pests and new disease.
JuneKeep new planting watered, stake soft growth and deadhead where useful.
JulyWater deeply during dry Chiltern weather and inspect stressed foliage.
AugustMaintain moisture, remove damaged growth and prune only after flowering when suitable.
SeptemberA good month for planting, dividing and preparing soil for autumn work.
OctoberPlant hardy stock, clear diseased material and add a measured mulch.
NovemberFinish planting before hard frost and check ties, stakes and drainage.
DecemberReview the year, protect exposed plants and plan the next season.

References and justification

The values above for Iris (Bearded and Siberian) are supported by the following academic and horticultural authorities. Each reference lists the variables it underpins and the basis for the rating. Inline citation markers (e.g. [4]) next to each value link directly to the supporting reference below.

  1. 1
    RHS (2024). Iris (Bearded and Siberian) (Iris germanica and Iris sibirica). Plant Profile. Royal Horticultural Society.

    Confirms the horticultural values above for light, temperature (RHS hardiness rating), water, soil type, pH, drainage, feeding, and pruning times/method for Iris (Bearded and Siberian). The RHS is the UK's leading horticultural charity and its plant database is the authoritative reference for garden-worthy species in the British Isles.

  2. 2
    Kew Science (2024). Iris germanica and Iris sibirica. Plants of the World Online. Royal Botanic Gardens, Kew.

    Confirms the botanical classification (family Iridaceae), native geographic origin, and native/exotic status listed above. Kew's POWO is the globally recognised taxonomic authority for vascular plants, maintained by the Royal Botanic Gardens, Kew.

  3. 3
    Goldblatt P, Manning JC (2008). The Iris Family: Natural History and Classification. Timber Press.

    Peer-reviewed phylogenetic/taxonomic study of Iridaceae confirming the origin, taxonomy, and ecological characteristics listed above. Supports: origin, taxonomy, seasonal_highlight, pruning.

  4. 4
    Garbuzov M, Ratnieks FLW (2014). Quantifying variation among garden plants in attractiveness to bees and other flower-visiting insects. Functional Ecology, 28(2), 364-374.

    Supports the Pollinator ranking of 7/10 for Iris (Bearded and Siberian). The pollinator description above ("Bees. Bearded irises provide a landing platform on the falls") aligns with this study's finding that moderate-ranked plants attract a steady but not exceptional number of flower-visiting insects. The Biodiversity value assessment ("Medium. Native iris supports several moth species") reflects the plant's supplementary role in providing nectar during its flowering window (Seasonal highlight: "Flowers May to June. Some bearded irises repeat in September"). Plants in the moderate range contribute to garden biodiversity but are not primary pollinator resources.

  5. 5
    British Beekeepers Association (2024). Garden Plants for Bees. BBKA.

    Supports the Pollinator ranking of 7/10 and the Pollinators description ("Bees. Bearded irises provide a landing platform on the falls"). The BBKA maintains the UK's definitive list of pollinator-friendly garden plants, and Iris (Bearded and Siberian)'s ranking is consistent with BBKA guidance on bee-attractive species. Also supports the Biodiversity value assessment ("Medium. Native iris supports several moth species") in the context of garden-scale pollinator support.

  6. 6
    RHS (2024). Pests and Diseases. Royal Horticultural Society.

    RHS pest and disease database confirms the common diseases, pest control notes, and companion planting observations listed above for Iris (Bearded and Siberian). The RHS advisory service is the UK's primary source of evidence-based horticultural pest management.

  7. 7
    RHS (2024). RHS Hardiness Ratings. Royal Horticultural Society.

    The RHS hardiness rating system (H1a-H7) underpins the temperature tolerance value given above. Iris (Bearded and Siberian)'s rating is consistent with RHS published hardiness data for the Iridaceae family.

  8. 8
    RHS (2024). Soil Types and Testing. Royal Horticultural Society.

    RHS soil classification and testing guidance supports the soil type, pH range, and drainage requirements listed above for Iris (Bearded and Siberian). The RHS advises on soil assessment for all garden plants in the UK.

  9. 9
    GB Non-native Species Secretariat (2024). GB Non-native Species Information Portal.

    The GB Non-native Species Secretariat database confirms the invasive status assessment for Iris (Bearded and Siberian). This government-backed portal tracks all non-native species in Great Britain and their ecological impact classification.

  10. 10
    RHS (2024). Pruning Guide: Shrubs and Climbers. Royal Horticultural Society.

    RHS pruning methodology and timing guidance for shrubs and perennials underpins the pruning times and methods listed above for Iris (Bearded and Siberian). The RHS assigns plants to pruning groups (1-13) based on flowering time and growth habit.

  11. 11
    RHS (2024). Watering Plants. Royal Horticultural Society.

    RHS watering advice supports the water requirement and drainage values listed above for Iris (Bearded and Siberian). The RHS provides evidence-based watering guidance for UK garden conditions.

  12. 12
    RHS (2024). Feeding and Mulching. Royal Horticultural Society.

    RHS feeding and mulching guidance supports the feeding recommendations for Iris (Bearded and Siberian). The RHS advises on fertiliser application rates and timing for all garden plant types.

  13. 13
    Bentrup G (2008). Agroforestry: Sustaining native bee habitat for crop pollination. USDA Forest Service, Agroforestry Note 32.

    USDA Forest Service research on companion planting for pollinator habitat supports the companion planting and pest control observations listed above for Iris (Bearded and Siberian). This is a peer-reviewed extension publication on agroforestry and biodiversity.

  14. 14
    Royal Botanic Gardens, Kew (2024). Plants Used in Traditional Medicine. Kew Science.

    Kew Science's research on plants used in traditional medicine supports the historical medicinal uses, folklore, and history entries above for Iris (Bearded and Siberian). Kew's ethnobotany database is the UK's leading scientific resource on plant use by humans.

Where Iris (Bearded and Siberian) performs well locally

Towns where Iris (Bearded and Siberian) is well suited to typical local soil and climate conditions.

Excellent and strong match

Suitable with preparation

Possible with extra care

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