How do I remove blanketweed from a pond?

Lift excessive blanketweed out carefully with a net or by hand, then leave the removed growth beside the pond briefly so small animals can return to the water. After that, compost it unless you suspect it contains a legally controlled invasive plant.

Some algae are normal and provide cover, so a wildlife pond does not need to be stripped clean. The RHS advises disturbing wildlife ponds as little as possible. If growth is heavy, reduce the conditions that feed it: keep soil, fertiliser and decaying leaves out; use rainwater where possible; and add suitable plant cover without allowing the surface to close completely.

Do not buy a UV clarifier to solve blanketweed. UV equipment targets the suspended algae behind green water, not long attached strands. Avoid emptying and refilling the pond as a routine cure; the RHS says that can make the long-term problem worse.

Remove it without stripping the habitat

Work around the pond in small sections. Wind loose strands around a stick or lift them with a net, taking care around spawn, tadpoles and planted baskets. Do not drag tools across a liner. Check the removed mass for animals, then leave it on the bank briefly as official wildlife guidance recommends. Repeat when necessary instead of trying to sterilise the water in one session. Keep a note of when heavy growth returns; repeated blooms point back to sunlight and nutrient inputs rather than a failure to remove enough strands.

Rinse tools over the pond, not over a drain or another water body.

Sources

• RHS: pond algae and blanket weed — accessed 14 November 2026.
• Natural History Museum: garden pond questions — accessed 14 November 2026.

More from Pond Setup Guide

Follow the blanketweed guide and compare green pond water. Blanketweed and algae are defined in the pond glossary.