Hypericum perforatum

RHS Plant Profile
perforate St John's wort

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perforate St John's wort visionspictures.com
perforate St John's wort visionspictures.com

Other common names

cammock, common St John's wort, devil chaser, devil's flight, devil's scourge, eurinllys trydwll, God's wonder plant, herb John, human blood, Klamath weed, penny John, rosin rose, St Columba's flower

Synonyms

Hypericum lineolatum

RHS Recommended

Plants for pollinators
Herbaceous Perennial
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A clump-forming, upright perennial to about 1m tall, the small, narrow oval mid-green leaves with translucent dots that give the appearance of perforations, and broad, pyramid-shaped terminal clusters of star-shaped yellow flowers to 2cm across, in summer

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

1-1.5 metres

Max Spread

0.5-1 metres

Size

Time to Maturity
2–5 years
Max Spread
0.5-1 metres
Max Height
1-1.5 metres

Growing Conditions

Chalk Clay Loam Sand
Moisture
Moist but well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun Partial shade
Aspect
South–facing or West–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)
H6

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 the Environment

  • For Wet & Dry Conditions

For Bio-Diversity

  • Plants for Pollinators

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Hypericaceae
Native to GB/Ireland
Yes
Foliage
Deciduous
Habit
Clump forming
Potentially harmful
Fruit are ornamental - not to be eaten. Wear gloves and other protective equipment when handling. Pets: Fruit are ornamental - not to be eaten - see the HTA guide to potentially harmful plants for further information and useful contact numbers
Genus
Hypericum can be annuals, perennials, shrubs or trees, evergreen or deciduous, with usually paired leaves and showy yellow flowers with prominent stamens, followed by capsules, occasionally berry-like
Name Status
Correct
Plant Range
Europe, N Africa, SW Asia

How to Grow

Cultivation

Grows well in moist but well-drained soil in full sun or part shade. Ideal for wildflower garden, wild garden or informal borders. ?See hypericum cultivation for further advice

Propagation

Propagate by seed, division or take softwood cuttings

Suggested planting locations and garden types

  • Cottage and informal garden
  • Wildflower meadow
  • Wildlife gardens
  • Flower borders and beds

Pruning

No pruning required other than a tidy before spring growth commences

Pests

Generally pest-free

Diseases

May be susceptible to honey fungus (rarely)