Iris pseudacorus 'Roy Davidson'

RHS Plant Profile
yellow flag 'Roy Davidson'

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Synonyms

Iris 'Roy Davidson'

RHS Recommended

Award of Garden Merit Plants for pollinators
Herbaceous Perennial Bogs
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A clump-forming perennial to 1.1m, the stems with 10 flowers or more, light yellow with light brown veining, the falls with a crescent-shaped brown central flash

Position

Full sun, Partial shade

Soil Types

Clay, Loam

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
0.5-1 metres

Growing Conditions

Clay Loam
Moisture
Moist but well–drained or Poorly–drained
pH
Acid

Position

Full sun Partial shade
Aspect
West–facing or South–facing or East–facing
Exposure
Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

  • H1A: under glass all year (>15C)
  • H1B: can be grown outside in the summer (10 - 15)
  • H1C: can be grown outside in the summer (5 - 10)
  • H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
  • H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
  • H4: hardy through most of the UK (-10 to -5)
  • H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
  • H6: hardy in all of UK and northern Europe (-20 to -15)
  • H7: hardy in the severest European continental climates (< -20)
H7

RHS Recommended: for People & Planet

RHS Recommended Plants for People & Planet

For Water Resilience

Plants for Flood Resilience

Plants that can help manage heavy rain by catching rainfall, slowing surface run-off, encouraging water into the soil or taking it up through their roots, contributing to flood resilient gardens.

Plants for both Wet and Dry Conditions

Plants that cope with changing soil moisture, including wet winters and extended summer dry. Once established, they grow as wet and dry conditions alternate.

For Temperature Resilience

Plants for Temperature Cooling

Plants that cool air temperature by providing shade, transpiration, or reflection to reduce heat impact on people, animals, soil or other ground surface.

Plants for Wind Shelter

Plants with dense canopies often grown as a tall thick hedge or grouping can block wind and shelter gardens, buildings and people.

For Carbon Storage

Plants for Carbon Storage

Plants that can take up carbon (CO₂) through photosynthesis and store it within the plant or deposit it by their roots into the soil.

For Biodiversity

Plants for Pollinators

Plants that have flowering properties (pollen and/or nectar) that are particularly beneficial for pollinating insects such as bees, butterflies and hoverflies.

Growing conditions for maximum benefit

This plant will provide the maximum benefits if it is healthy and allowed to grow to maturity

For Bio-Diversity

  • Plants for Pollinators

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Iridaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Potentially harmful
Harmful if eaten. Wear gloves and other protective equipment when handling. Pets: Harmful if eaten. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus
Iris may be rhizomatous or bulbous perennials, with narrow leaves and erect stems bearing flowers with 3 large spreading or pendent fall petals, alternating with 3 erect, often smaller, standard petals, in late winter, spring or early summer
Name Status
Accepted

How to Grow

Cultivation

Grow in moist to wet, deep, humus-rich, acid soil; it thrives at the margins of large ponds or streams; has the potential to become a nuisance if not managed well so plant with care

Propagation

Propagate by division of rhizomes from midsummer to early autumn

Suggested planting locations and garden types

  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Wildlife gardens
  • Flower borders and beds

Pruning

Remove any dying foliage in autumn, old flower stems can be cut down after flowering

Pests

May be susceptible to slugs, snails and thrips

Diseases

May be susceptible to aphid-borne viruses, bacterial soft rot and grey moulds; see iris diseases