Compost with care

Don't dump aquatic plants in the wild - you could be breaking the law. The plants can become invasive and damage the environment. The information below provides guidance on how to manage your pond and plants.

Charlie Dimmock is supporting the Be Plant Wise campaign by encouraging pond owners to compost unwanted pond plants.

Female gardener sat by pond holding weeds in hand

What should I do if I find invasive aquatic plants in my pond?

  • Act quickly - if you find you have an invasive plant and want to remove it, act quickly. Waiting a
    few weeks or months could allow the plant to spread.
  • Remove every last bit - most invasive species can re-grow from tiny fragments, so try to remove every last bit. You won't always get everything so make sure to check for re-growth in the following season and remove new plants as necessary.
  • Time your work - problem plants can be pulled out at anytime, but big clearouts should be saved for autumn, when they will cause the least disturbance to your pond.
  • Clean your kit - make sure to clean your footwear and equipment when removing unwanted
    plants. Tiny fragments could be carried on them and regrow.
  • Don't spread plants with your waste water - any waste pond water should be emptied away from streams, rivers, ponds, lakes and lochs, or drains that flow into them. You could use the excess water on the lawn or to water plants in your garden.
  • Protect pond life - before disposing of plants leave them for a few hours beside the water, so that pond animals can return to the pond.
  • Don't dump your plants in the wild - if you dump any of your aquatic plants in the wild you could be breaking the law. [In Scotland it is already illegal to introduce (e.g. by disposing of waste material) four of the five invasive species we have listed in the wild, and from 6 April 2010 in England it will be illegal to introduce all five in the wild.]

Tips for dealing with five invasive plants that are causing problems

Getting rid of some of the worst invasive species can take some time and a number of growing seasons. It is important to remove as much of the plant material as possible, while avoiding breaking it into many small pieces which could encourage spread. By regularly checking for and removing re-growth you should be able to keep these plants under control. Here are some tips for controlling five problem plants.

Floating Pennywort (Hydrocotyle ranunculoides)

In short: Repeated cutting / pulling is usually necessary. You'll need to re-visit and regularly clear out any new growth.

Floating Pennywort is difficult to control due to its rapid growth rates (up to 20cm per day!) and its ability to re-grow from a small fragment. Regular cutting from May-October will prevent complete dominance and so help manage this plant. Cut material needs to be removed from the water immediately. Hand pulling (or spot chemical treatment) should follow cutting to reduce re-growth. Pulling is likely to work best on small infestations rather than larger areas. Chemical treatment should only be used at the end of the growing season when all other plants have died back.

Parrot's feather (Myriophyllum aquaticum)

In short: Uproot it manually as soon as you notice it.

Regular cutting (at least every 6-9 weeks during the growing season - cut more frequently if necessary) will help to weaken the plant. In your garden pond you can thin using a rake. Cut material must be removed from the water as soon as possible and all fragments need to be removed to prevent re-growth (or spread downstream if you are clearing an area of river). Careful pulling out of stems by hand after cutting will help eradicate it.

New Zealand pigmyweed also known as Australian swamp stonecrop (Crassula helmsii)

In short: Pull it out as soon as you see it. You'll need to re-visit and regularly clear out any new growth.

Early and regular treatment is highly recommended. In small ponds, regular pulling out of the plant may be an effective control technique. New Zealand pigmyweed does seem to be less vigorous in ponds with plants that provide some shade, like the native bogbean Menyanthes trifoliata for example. Shading by covering with black polythene for at least three months during the growing season can also be effective, although this will have adverse effects on other species in the pond.

While herbicides can be used to help control this plant, they should only be used in winter months when all other plants have died back. However, any use of herbicide in ponds will cause damage to other species and should only be undertaken where pigmyweed has completely invaded the pond.

Water-primrose (Ludwigia grandiflora, Ludwigia uruguayensis or Ludwigia peploides also sold incorrectly as Jussiaea)

In short: Pull it out as soon as you see it. You'll need to re-visit and regularly clear out any new growth.

Early removal is essential if this plant is to be controlled. Try to remove all plant fragments and roots, otherwise re-infestation may occur. Regular clearing may be required to deal with re-growth.

Water fern - also known as fairy fern (Azolla filiculoides)

In short: Remove from the surface of your pond with a net before spores are released (spores are released at the beginning of winter or once dense mats have formed).

The easiest way to ensure you get all of the plant matter out of your pond is to scoop it up with a net. The RHS suggest that by disturbing the water surface, fountains may help to reduce infestations. In larger ponds and lakes, a floating boom can be used to sweep the water surface. Complete control is very difficult and so repeated clearance will be necessary.

It is important to attempt control before the spores are released (at the beginning of winter, or once dense mats have formed). If spores have already been released then be extra vigilant the following year to catch re-infestation early.

How to dispose of your pond plants

  • Compost or green waste only - you should always dispose of plants by composting them or using your local green waste.
  • Never place them in a nearby pond or waterway, where they can quickly become a problem.
  • Don't dump your plants in the wild - this could be illegal and the plants could damage the environment.

For more advice on composting and green waste visit:

How do I look after my pond?

  • Many people think that good ponds need to have lots of open water, a narrow fringe of attractive wetland plants around the edge, a deep bit in the middle, no trees around it and lots of sunshine, but this is just one type of pond. For garden ponds, shallow water is often better for wildlife.
  • It's important to keep the water as clean and unpolluted as you can: in gardens, in many parts of the country, it's a good idea to avoid using tapwater and instead collect rain water.
  • While wildlife ponds may need less management than other ponds - all ponds need to be managed so that plants don't take over.
  • If you have a garden pond, try doing a dip with a basic sieve and a white tray - you might be surprised to find out how many different things are living in there. If you are working on a larger pond, it's a good idea to assess the risk of damaging existing wildlife interest before managing the pond, or getting a professional survey done.
  • If you find non-native invasive aquatic plants in your pond, and decide to remove them, you must do so with utmost care so as to avoid spreading them. (See additional information below on what to do).
  • If you want to help a plant or animal that prefers a more open pond, consider creating a new pond instead of changing the existing pond and risk losing a lot of wildlife.
  • Another great thing about making a new pond is that you can make sure it has clean water, away from sources of pollution. Rainwater is often best for this, because clean water is vital for really diverse wildlife ponds, as well as preventing excessive growth of algae.
  • For advice on managing your pond or making a new one, you can visit

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