Rosebay willowherb
The tall, pretty pink flower spikes of rosebay willowherb (Chamaenerion angustifolium) are a common sight on railway banks and disturbed woodland. It is a useful nectar source for pollinators but self-seeds readily and can become a troublesome garden weed.
Quick facts
Botanical name Chamaenerion angustifolium
Synonyms Chamerion angustifolium, Epilobium angustifolium
Area affected Disturbed ground
Caused by Windborne seed and branching underground stems (rhizomes)
Timing Flowers June to September; treat spring to autumn
What is rosebay willowherb?
Chamaenerion angustifolium is a native perennial weed which spreads by seed and
A white
Rosebay willowherb is a valuable food source for numerous species of moths and butterflies; it is also a useful nectar source for pollinators, including bees.
Bees in your garden
Butterflies in your garden
Moths in your garden
The white or pink flowered rosebay willowherbs may be welcomed by gardeners wishing to fill large borders, but in smaller gardens some control measures may be needed. This page looks at options for gardeners when rosebay willowherb is becoming a problem.
Appearance
The problem
Control
The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.
Cultural control
Cultural methods such as hoeing and forking-out are effective against this shallow-rooted weed. Opaque mulching films can also be used to suppress its growth around woody plants or on unplanted beds.
Weedkiller control
The RHS does not support the use of weedkillers and recommends that alternative control methods are used. However, we do note that when gardeners struggle to control plants with cultural methods, regulated weedkillers/pesticides for home gardeners are available for use legally. Garden centres and large retailers selling weedkillers have trained staff who can advise on suitable products for your needs.
Get involved
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.