Hypericum perforatum

RHS Plant Profile

perforate St John's wort

Other common names

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

Synonyms

Hypericum lineolatum

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

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

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)