Pruning Aquatic Plants
It is important to regularly prune and thin out aquatic plants in order to keep the pond neat and tidy and to prevent the water from become too rich in nutrients.
Pruning is mainly a question of avoiding too much vegetative waste in the pond, so you should regularly consider which stems and leaves are to be removed.
If the flowers of the ordinary hardy water lilies in your pond grow to a height of five to ten centimetres above water level, it is high time to rejuvenate the plants. This can be done in summer. The ideal period is from June to the end of August.
Throw away the oldest, lowermost part of the rootstock, keeping the vigorous top shoot with a piece of rootstock of about ten to fifteen centimetres. Place this pointing slightly upwards in a water lily basket filled with a mixture of pond soil and loam. Place the root in the basket so that the wound is in the corner of the basket and the shoot points diagonally towards the middle of the basket. This means that it has the longest possible distance to grow before reaching the opposite side of the basket.
As water lilies are vigorous growers that need extra nutrition, it is recommended to add a pond fertilizer tablet to the water every year.
Thinning out aquatic plants prevents dead branches and leaves from decomposing in the water, thus reducing the risk of rotting or excessive nutrients in the water.
Waterside plants such as reed-mace and yellow flag can be very invasive. You can stop these plants from taking over the entire pond by regularly cutting off the runners.
Make sure you cut the stems of marsh plants above the ground, otherwise the plant may rot! Floating oxygen plants can also proliferate rapidly, so it is advisable to thin these out once a year.