Trillium grandiflorum f. polymerum 'Flore Pleno' (d)

RHS Plant Profile

double-flowered American wake-robin

RHS

Other common names

double-flowered American wake robin

Synonyms

Trillium grandiflorum 'Flore Pleno'
Trillium grandiflorum flore-pleno

Herbaceous Perennial

Buy this from Plant Nurseries
3 Suppliers

A clump-forming herbaceous perennial to 40cm, with large, broadly ovate leaves and solitary, fully double, pure white flowers 8-12cm across in spring and early summer

Position

Full shade, Partial shade

Soil Types

Chalk, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

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

Growing Conditions

Chalk Loam Sand

Moisture: Moist but well–drained
pH: Acid or Neutral

Position

Full shade Partial shade

Aspect: North–facing or West–facing or East–facing
Exposure: 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): H5

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Melanthiaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Bushy
Genus: Trillium are rhizomatous, herbaceous perennials with erect stems bearing a whorl of ovate or diamond-shaped leaves, with one or more erect or nodding flowers borne at the stem apex
Name Status: Accepted

How to Grow

Cultivation

Grow in deep, moist but well-drained, humus-rich, preferably acid to neutral soil in deep or partial shade. Mulch in autumn with leaf mould. See trillium cultivation

Propagation

Propagate by seed in pots in a shady cold frame as soon as seed is ripe; takes 5-7 years to reach flowering size. Propagate rhizomes by division after flowering or cut out the growing point from the rhizome after flowering, which stimulates the formation of offsets

Suggested planting locations and garden types

Cottage and informal garden
Underplanting of roses and shrubs
Flower borders and beds

Pruning

No pruning required

Pests

May be susceptible to slugs and snails

Diseases

Generally disease-free