Skip to main content

The charity making life better by water

Eradicating Himalayan balsam in new ways

Using only natural materials, we're monitoring a trial site at the Penarth Feeder to see whether this innovative method will be successful in the fight against Himalayan balsam.

Invasive non-native species are one of the top three threats to biodiversity on a global scale.

Through our award-winning Canal & River Invasive Species Eradication Project, we're working hard to eradicate their presence from our waterways.

Though it may look and sound appealing, Himalayan balsam can grow between 2-3m in height. Due to the large amount of seeds each plant produces, it can form dense areas of growth, crowding out native wildflowers and plants, and preventing them from getting the natural light and nutrients they need to survive.

Until now, chemicals and manual pulling have been the only ways to treat this problematic plant.

Himalayan Balsam with purple flowers on both banks of narrow waterway

How is this new trial eco-friendly?

Rather than relying on chemicals, this trial uses only natural materials.

What has the trial involved?

To begin with, the Penarth Feeder was dredged, which involves removing silt from the bottom of the water.

This is already a positive action, as a build up of silt in our waterways can cause problems for wildlife by de-oxygenating the water and clogging the gills of fish. It also makes it harder to navigate boats.

The collected silt was then placed on top of a biodegradable hessian matting above the Himalayan balsam seed bank, to snuff out the plant and prevent it from growing.

The next stage was then to hydroseed the bank with native wildflowers and grasses, to help encourage biodiversity back into the area.

Dredging and prepping the trial area

What are the results so far?

After six months, we're delighted to see very limited regrowth of Himalayan balsam on the bank, and instead an appearance of a variety of native plant species.

This is in contrast with steeper areas of the bank that were left untreated, where Himalayan balsam is clearly visible.

How will these areas continue to be managed?

The isolated regrowth of Himalayan balsam within the trial area can be easily maintained by mowing and removal by hand.

To the right of the feeder, there is a noticeable difference between the treated and untreated areas

Will this project be expanding as a result of its success?

In our first year of trialling, we've already covered 195km of our waterways. The plan will be to roll this out further with the support of our partners and volunteers.

How you can join the fight against invasive non-native species (INNS)

If you spend time on our canals and rivers, one of the most important things you can do is to remember to Check, Clean, Dry. These steps help stop the spread of harmful plants and animals to a new area, and should always be done before exiting a waterway, even if you are moving to another spot just a few miles away.

If you would like to volunteer on this project with us, we are currently looking for someone to help out with admin and reporting. Please contact Charles Hughes for more information.

Last Edited: 28 May 2024

photo of a location on the canals
newsletter logo

Stay connected

Sign up to our monthly newsletter and be the first to hear about campaigns, upcoming events and fundraising inspiration