Weed Of the Week Rosebay Willow Herb

Laurence Gale MScin Consultancy

Weed of the Week: Rose bay Willow Herb(Chamaenerion angustifolium)

By Laurence Gale MSc

Rose Bay Willow Herb Weed

What is a weed? By definition a weed is a plant that is growing in the wrong place. Weeds take valuable space, water, sunlight and nutrients that may otherwise be accessible to important crops, in our case turf grasses. Weeds not only compete for these resources they can disfigure and cause problems to playing surfaces.

Weeds are very good competitors and take advantage of any opportunities to colonise turf situations, particularly when the sward is under stress and weak, leaving bare soil areas for weeds to populate. Weeds have many mechanisms and characteristics that enable them to do this, having thick waxy cuticle leaves that can be resistant to some chemicals, fast reproduction methods, the ability to reseed in 6 week cycles and deep tap roots enabling the weed to survive in compacted dry ground conditions.

Weeds have one of three life cycles: annual; biennial or perennial.

  • Annual weeds: Live for a single season. These weeds germinate from seed in the spring or summer, flower and then die.

  • Biennial weeds: Live for two seasons. During the first growing season, these weeds remain in a vegetative stage and, in the following year, produce flowers, set seed and die.

  • Perennial weeds: Live for multiple seasons and flower more than once. Perennial structures (rhizomes, stolons, crowns, entire plants or roots) survive from year to year.

Some weeds may be harmful to the environment or noxious to your regional ecology. For example Japanese Knotweed (Fallopia Japonica) is fast becoming a major weed problem on road side verges and urban landscape areas, a very difficult weed to eradicate. It is very important to recognise weeds and seek effective controls methods to eradicate them from our facilities.

Weeds can also be used as an indicator of soil conditions. For example, knotweed and plantains both indicate soil compaction because they can maintain adequate root respiration at lower oxygen diffusion levels than other plants. Different weeds tolerate different soil conditions, some are alkaline loving and others acid loving. Getting to understand and recognise the physiology of these plants will help you become better turfgrass managers.

This weeks weed is: Chamaenerion angustifolium (Rose bay willow herb)

Scientific name


Life cycle

Chamaenerion angustifolium



Form / Appearance

Size: Grows to a height of around 110cms.Common in disturbed ground, along forestry rides, as a garden weed, or on abandoned land. This weed can be seen throughout the United kingdom.


Willow herbs have fine shallow rhizome root systems that can colonise areas quickly.


Flowering months: June to September. Flowers rose pink, 15 or more in spikes at the top of stem. Once pollinated the flower produce seed pods that can hold between 300-600 seeds. The seeds produce a tuft of hair (parachute) which helps in the dispersal of the seeds when ripe.


Leaves are alternate, narrow and lance shaped, 75-150mm long forming on long stems 1-15m tall

Reproductive method

In early autumn the plant produces hundreds of seeds, each equipped with a hairy parachute. Even a gentle breeze will carry the seeds over a large distance to colonise new areas.


Hedgerows, roadsides and waste ground. Willow Herb grows on any waste ground, or newly cultivated land, particularly when the seed bank as been disturbed thus stimulating germination of any seed in the ground.

Special features: Sometimes called 'fireweed', because it thrives on areas where there has been a bonfire. The heat from the fire actually helps the seeds to germinate.

Miscellaneous info

Other common names include: Common Fireweed, Perennial Fireweed, Narrow Leaved Fireweed, Great Willow Herb, Rosebay, Rosebay Willow Herb, Blooming Sally, Blood Vine.

The leaves, shaped like those of the willow tree (hence the name).

Cultural Control

Hand weeding before flowering. Important to remove as much root growth as possible, or continuous cutting down will eventually exhaust plant populations.

Chemical Control

Apply total herbicides when plant growth is active. There are a number of products available for controlling Perennial weeds.

Casoron G can be used as a pre- nd post emergence residual herbicide for use around rose, tree and shrub beds, in non cropped land and in aquatic places.

For sensitive environments including waterways, Roundup® Biactive is an excellent product that can be applied to weeds in channels, drains, streams, rivers.

These chemicals are best used when the weeds are actively growing, usually between April-October.

  • Casoron G (Contains 6.75% w/w dichlobenil) Rigby Taylor

  • Timbrel. (Contains 480g per litre triclopyr). Rigby Taylor.

  • Roundup Biactive. A translocated non-residual phosphonic acid herbicide (Contains: 360 g/l glyphosate, present as 480 g/l (41.1% ww) of the isopropylamine salt of glyphosate). Monsanto.

These herbicides are usually applied as a liquid using watering cans, knapsack sprayers and vehicle mounted sprayers.

Ensure you follow manufacturer's directions, health & safety and product data sheets, and comply with COSHH regulations, when using these chemicals.

Herbicides are an effective tool where high quality turf is desired. However, they must be applied with care and accuracy and in the context of a good overall turf management program. Before using any herbicide, carefully review the label for conditions of use including rates, methods of application, and precautions. Never use an herbicide in any manner contrary to its label and be sure that the herbicide will not injure the turfgrass species

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