The short answer

Quick Answer

Camassia thrives in full sun or full shade on most soils (pH 5.5-7), free-draining. Reaches 60cm to 1.2m tall. plant 20cm apart. Hardy to around -20°C.

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

On this page

Pruning

When: None. Let leaves die down naturally

How: Cut flower spike down once seed has set if you do not want self-seeding. Let leaves yellow

Origin, history and folklore

Origin: Western North America from Canada to California

Native or exotic: Exotic

History: Camassias reached Europe from North America in the early 1800s. They were first described by Meriwether Lewis of the Lewis and Clark expedition in 1806

Folklore: The name quamash comes from the Nez Perce word for the bulb, which was pit-roasted for days to make it edible

Fun fact: Camassia bulbs were a major food source for Native American tribes of the Pacific Northwest, who harvested them in such quantities that the bulbs were traded as currency

Historical medicinal uses: Bulbs were used as food, not medicine. Cooking is complex and the raw bulbs are indigestible

Wildlife and biodiversity

Pollinators: Bees and hoverflies love the open starry flowers. Excellent for late spring pollinators [4][5]

Pollinator ranking: 9 out of 10 (10 means a lot of pollinators, 1 means little) [4][5]

Biodiversity value: 6 out of 10 Medium. Provides nectar in the May gap when few bulbs flower[4][5][13]

Seasonal highlight: 8 out of 10 Flowers May to June. Long-lasting spires over several weeks[3][4]

Companion planting and pests

Companion planting: Plant with late tulips, fritillaries, alliums and early irises in long grass

Pest control: Generally pest free

Common diseases and issues: Generally trouble-free. Slugs on new shoots. Occasionally virus diseases. See RHS bulb rot advice

Invasive note: Not invasive. Self-seeds gently where happy

CGM care note

We plant camassia bulbs in October at 10 to 15cm deep and 20cm apart in moist soil that does not dry out in spring, where most bulbs would rot. They are ideal for the damp edges of a wildflower meadow and we let them self-seed into long grass for a natural look. Lift and divide congested clumps in July when dormant.

Useful resources

Plant relationships, Camassia

How Camassia 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

  • Hydrangea, shares moisture preference, plant together in damp spots or near water features
  • Astilbe, shares moisture preference, plant together in damp spots or near water features
  • Hosta (Plantain Lily), shares moisture preference, plant together in damp spots or near water features
  • Hardy Garden Ferns, shares moisture preference, plant together in damp spots or near water features
  • Japanese Anemone, shares moisture preference, plant together in damp spots or near water features
  • Daffodils and Narcissi, spring/summer flowering bulbs, plant among perennials for early season colour

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 Camassia.

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 Camassia 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). Camassia (Camassia quamash and Camassia leichtlinii). 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 Camassia. 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). Camassia quamash and Camassia leichtlinii. Plants of the World Online. Royal Botanic Gardens, Kew.

    Confirms the botanical classification (family Asparagaceae), 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
    Seberg O, Petersen G, Davis JI, et al. (2012). Phylogeny of the Asparagales. Aliso, 30(2), 77-84.

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

  4. 4
    Hicks DM, Ouvrard P, Baldock KCR, et al. (2016). Food for pollinators: quantifying the nectar and pollen resources of urban flower meadows. PLOS ONE, 11(6), e0158117.

    Supports the Pollinator ranking of 9/10 for Camassia. The pollinator description above ("Bees and hoverflies love the open starry flowers. Excellent for late spring pollinators") is consistent with this study's finding that plants in the high-nectar-yield category attract exceptional numbers of bees, butterflies, and moths. The Biodiversity value assessment ("Medium. Provides nectar in the May gap when few bulbs flower") is supported by the study's quantification of nectar resources during the mid-summer flowering period (Seasonal highlight: "Flowers May to June. Long-lasting spires over several weeks"). Plants with high floral resources are disproportionately important for sustaining pollinator populations in domestic gardens.

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

    Supports the Pollinator ranking of 9/10 and the Pollinators description ("Bees and hoverflies love the open starry flowers. Excellent for late spring pollinators"). The BBKA maintains the UK's definitive list of pollinator-friendly garden plants, and Camassia's ranking is consistent with BBKA guidance on bee-attractive species. Also supports the Biodiversity value assessment ("Medium. Provides nectar in the May gap when few bulbs flower") 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 Camassia. 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. Camassia's rating is consistent with RHS published hardiness data for the Asparagaceae 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 Camassia. 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 Camassia. 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 Camassia. 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 Camassia. 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 Camassia. 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 Camassia. 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 Camassia. Kew's ethnobotany database is the UK's leading scientific resource on plant use by humans.

Where Camassia performs well locally

Towns where Camassia is well suited to typical local soil and climate conditions.

Excellent and strong match

Suitable with preparation

View all areas we cover