Pond Weeds. Blanket Weed and Duck Weed.

Spring is the season of plant activity as they emerge from winter dormancy. Weeds in the pond also start to emerge in the early month after a few months hidden away.

A pond well-stocked with aquatic plants seems to fare better than a bare pond insofar as weed infestation is concerned. This is probably because of the lower light intensity and lowering of nutrients in the water which seems to deter some weeds. There are basically two types of pond weeds. those that float on the water, and those who spend their entire pond life submerged below the surface.

Blanket weed

is an algae which uses nitrogen and light present in the water with which to survive. As its name suggests, Blanket Weed quickly forms a dense mat of growth that can soon choke a pond and its inhabitants. If the blanket weed gets a good start to life then it can become a serious problem. However, because of its very nature of growth, great lumps of it can be scooped up with a garden rake dragged through the pond.

Take care when disposing of the blanket weed scooped out by this method, as it can also contain many beneficial insects and creatures for the pond. Lay the scooped blanket weed at the edge of the pond overnight to allow inhabitants to make their way back into the pond.
There are chemical controls available for Blanket weed. However, two very effective methods of controlling and even preventing blanket weed are very simple.
- A hessian sack full of straw can be floated on the pond during the early spring. Hay can also be used, but straw seems to work better. The Nitrogen in the water that normally supports the Blanket Weed, will soon turn its attention to the straw in the natural process of decomposing the straw. the bacteria that assist in the rotting of the straw feed on the Nitrogen in the water - reducing its level quite considerably.
- With a smaller pond, a pair of tights filled with straw or hay can be used instead of the more bulky sack.
- Try to keep direct sunlight off the pond - preferably by using plenty of planting material. The algae deprived of light is rarely a problem.

Duckweed

Duckweed - rather attractive in small doses - is normally found on still water ponds, floating on the surface. The small clusters of leaves - bright apple green - soon multiply, and in spite of being a good source of food to some fish, will soon become a nuisance.

It has many benefits - not least being a good hiding place for small fish as they hatch. For the floating duck weed sends down stream of small roots which are great hiding places. Once it takes hold, it deprives the pond of light, so young emerging plants soon weaken. A 50 - 50 solution, is to weekly scoop out the quickly growing weed with a fishing net. The few bits you miss will soon develop and spread, so this really is a weekly operation.