Tweed Invasives Project

The Tweed Invasives Project started in 2002, when many stakeholders identified Giant Hogweed as one of the biggest threats to the River Tweed. With prolonged control of target non-native plant species, the Tweed Invasives Project is one of the UK’s largest and most successful control programmes. Whilst control of Giant Hogweed and Japanese Knotweed extends throughout the Tweed Catchment, the Project expanded to include Himalayan Balsam within the Till subcatchment in 2005. A brief history of the Project is available here and a more comprehensive review can be found in The Tweed Invasives Project: A Case Study.

Target Species

Giant Hogweed

Easy to identify when fully grown by height, size of leaves and size of flowers. Can be confused with native hogweed when not fully grown or when growth is stunted (e.g. regrowth after cutting). Read more…

Japanese Knotweed

Tall herbaceous perennial with bamboo like stems. Often grows into dense thickets. Characteristic leaves and stems, persistence of last year’s dead canes and distinctive rhizome (underground root-like stems) enables year-round identification. Read more…

Himalayan Balsam

A tall, attractive, annual herb with explosive seed heads. Although easy to identify as a mature plant with its pink-purple flowers, fleshy stem and characteristic leaves, the seedlings and last year’s dead stems of this annual are more difficult to spot. Read more…

Giant hogweed
Giant Hogweed
Japanese Knotweed
Himalayan Balsam

If you think you have seen one of these species or you need more information, please email us on giving your name, contact number, the exact location of which species and the date seen.

Find out more about how we are tackling the following species: Giant Hogweed, Japanese Knotweed, American Skunk Cabbage and Himalayan Balsam.

Find out more about how the project is progressing.


The Tweed Invasives Project is an integral part of the Tweed Catchment Bio-Security Planning Initiative (you can download the plan below). As part of our biosecurity planning we share information with the Tweed Foundation, who act on reports of invasive aquatic animal species within the catchment. You can report a sighting of an invasive aquatic animal, such as American signal crayfish, to the Foundation using this link


Tweed Catchment Bio-Security Plan (Plan, 2011-2016)
Controlling Invasive Plants in the Tweed Catchment (Leaflet, 2014)
Tweed Invasives Project: Summary Report (2016)
Assessment of Impact of Long Term Control of Invasive Non-native Riparian Plants in the Tweed Catchment and Restoration of Native Biodiversity (Report, 2013)
Tweed Invasives Project: A photographic record of progress between 2004 and 2009 (Photo Report, 2009)
The Tweed Invasives Project: The long-term control of Giant Hogweed and Japanese Knotweed; a case study of the Tweed and practical steps to establishing and delivering a successful, long-term control strategy (Report, 2006)

Other useful links