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Herbaceous Perennial

Epilobium ciliatum

American willowherb

A fast-growing, clump-forming herbaceous perennial to 1.5m high, with narrowly ovate, finely toothed green leaves often tinged with red, and numerous small, trumpet shaped pink or white flowers

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Ultimate height

1–1.5 metres

Time to ultimate height

1–2 years

Ultimate spread

0.1–0.5 metres

Chalk

Clay

Loam

Sand

Moisture

Moist but well–drained, Well–drained, Poorly–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full shade
Full sun
Partial shade

Aspect

East–facing or North–facing or South–facing or West–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)

Botanical details

Family: Onagraceae
Native to GB / Ireland: No
Foliage: Deciduous
Habit: Columnar upright
Genus: Epilobium can be annuals or perennials, sometimes invasive, with erect stems bearing willowy leaves and showy, 4-petalled flowers in terminal racemes
Name status: Unresolved

How to grow

Cultivation

Grows best in moist soil in well-lit conditions, but will tolerate shade and a range of soil types. Spreads rapidly, generally considered a weed

Propagation

Propagates by seed produced prolifically through the growing season and wind-dispersed. In favourable conditions, life cycle from germination to seed production can complete in ten weeks

Suggested planting locations and garden types

Pruning

No pruning required

Pests

Generally pest-free

Diseases

Generally disease-free

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