The battle with Giant Hogweed on the Water of Leith riverbanks began back in 2017, led by Charlotte. Since then, we’ve been spraying every year without fail, and over the last two years we’ve also been digging up seedlings in the spring.
Originally, our control work focused on the stretch from the Visitor Centre to Balerno due to staff capacity. However, as the project has grown, so too has its reach — now extending all the way down to Leith and up the Murrayburn tributary to Riccarton Garden Centre, as we continue to track down seed sources that get washed downstream.
Giant Hogweed is a non-native plant, first introduced into gardens around 1820 as an ornamental curiosity. It was often planted by rivers and ponds, where it has since spread aggressively. The plant outcompetes native species, reducing biodiversity along the riverbanks, and contains a toxic sap that can cause severe burns on contact with skin.
Committing to this project represents a significant investment for the Trust. Our sprayers require specialist training for chemical use, costing around £600 per person, and the work itself is extremely labour-intensive. Teams must wade along the riverbanks several times a year to ensure no plants are missed.
However, the results speak for themselves. As this year’s figures show, our consistent targeting — year after year — is reducing the number of plants along the banks, helping restore biodiversity and keeping the river safe and accessible for everyone to enjoy.
Since Giant Hogweed seeds can survive in the soil for up to five years, and with a large seed source recently discovered in the grounds of Riccarton Garden Centre, our work will continue into next year. Still, as the growing season comes to an end, it’s worth pausing to reflect on the real and measurable progress being made in this long-running battle.