Pond Weed
20 July 2006

There are two main weeds that cause trouble in ponds. Blanket weed appears in late spring as thick strands of bright green weed threading its way through the water. It may be removed by winding it around a stick or broom handle and pulling it out. It should be left close to the edge of the pond for 24 hours to allow insects to escape and return to the water. Blanket weed may be used in thin layers in the compost heap.

Duck weed is a floating weed made up of thousands of tiny plants with light green leaves. They float together forming sheets and quickly covering the surface of the pond. It's easily removed using a child’s fishing net or by skimming the surface of the water with a timber board and lifting out the weed.

The trouble is that if one piece of Duck weed is allowed to remain then it will quickly multiply, again covering the pond. Contamination is frequently the result of plant gifts from friends and keen gardeners. Wash the roots and foliage of all new aquatic plants to reduce the risk of duck weed before placing them in the pond .It is also carried on the feet of water fowl hence the common name.

Blanket weed is less of a problem where the water balance is good. Insects, aquatic plants and oxygenating plants help to achieve that balance. Where there is water movement that pushes oxygen into the pond that will also reduce the risk of weed.

Aggressive plants can be considered as weeds especially some of the large leafed lilies that cover the surface pushing their leaves out of the water. Oxygenating plants can grow rapidly smother smaller plants and filling small ponds with their foliage. In late spring and in early autumn the pond should be overhauled when spreading plants that are taking over can be curtailed.

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