Rosebay Willowherb

Rosebay Willowherb (epilobium angustifolium) and (chamerion angustifolium)

From the willowherb family Onagraceae, this weed is also known as Fireweed/Fire Weed, Great Willowherb, Rosebay and Willowherb/Willow Herb.

Originally from Great Britain, the more common name this weed
in the United States is Fireweed
and in Canada - Great Willowherb.

When Fireweed begins to grow
roots establish themselves beneath the soil surface with one main root spreading laterally supporting a plant that grows up to 6 feet tall.
Rosebay Willowherb

A rosette of leaves form on the soil surface and from this grow smooth stems. Narrow lance shaped leaves alternate up the stems as weed grows erect and on top are clusters of colorful pinkish-purple tiny blooms that form spikes flowering from June to September.

Although Rosebay Willowherb is ornamental looking and brings many pollinators, it is not at all recomended in any garden. This weed does become invasive.

It prefers poor acidic soils but can grow in alkaline soils as well. As long as there is space, light and exposed soil it will grow. When shaded out, Fireweed will die back. Seeds lie dormant until the right conditions apply for growth.

White flowered rosebay is becoming popular as a garden plant. Worth noting is all willowherbs produce a large number of tiny, highly disperesd seeds with the potential to become problematic.

Several of the smaller willowherbs, such as Dwarf Fireweed (epilobium latifolium) can become invasive. American (Epilobium ciliatum) and Broad Leaved Willowherb (Epilobium montanum) are the most common.

The name Fireweed was given because weed is often found growing in many burnt-out fields where there is little competition. In these environments this perennial weed is able to colonize and becomes very invasive. Fireweed also grows well in wet environments, woodland edges, waste areas and unfortunately it is becoming a problem in perennial crops.

For controlling and eradicating weed it is worth the time to have the pH of soil checked first. If soil is acidic adding lime to soil can help tremendously in controlling Fireweed.

Fireweed spreads by seed an creeping roots. Seeds capsules of plants have up to 500 seeds in them collectively producing about 80,000 per plant. It damages easily by cutting, trampling, grazing animals or burning. Remove manually by hoeing or hand pulling . Because fireweed likes wet environments roots usually aren't dry so there is a better chance of digging out all of root.

If using herbicides, non-selective post emergents in the fall is most effective. While nutrients carry down into the roots for storage during winter, the chemicals will carry to.


  • Don't confuse this with Rosebay the evergreen shrub commonly known as Oleander (Nerium oleander) from the Dogwood family.

    All parts of Oleander are toxic but is still a very popular garden plant. Rosebay Willowherb is edible for humans but is often food for field animals.

  • Angusti-folium is Latin and translates literally to narrow-leaf.

Related Articles:

Soil Testing Methods
Understand pH of soil and different soil testing methods.

How to Test Your Soil
Home testing soil pH ideas that help identify to your needs.

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