Removing blanket weed from a pondKeep an eye on aquatic and marginal plants, removing faded flowers and yellow leaves, and cutting back where necessary.

Top up water where necessary in ponds and water features. Aerate the water in hot sticky weather by leaving fountains on overnight.

Continue to remove blanket weed and duckweed using a net or rake.


Shallow water features or those with water washing over cobbles can become green very quickly in summer weather. Algicides may need applying more frequently than in normal ponds.

Clearing out fallen leaves and debris regularly will help to keep down algal growth, as there will be fewer nutrients available from rotting organic matter. Barley straw pads or extract may also be beneficial.

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.