Autumn - clean & maintain the pond

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Why should you clean & maintain your pond?

Answer: To avoid algae and blanketweed growth next Spring.

Maintain the pond every Autumn:

    1. Net the pond to stop tree leaves falling into the pond water
    2. Remove any tree leaves that reach the water with a dipping net while still on the surface
    3. Cut back most upright marginal plant vegetation to 15cm (6") above the Winter water level
    4.  Exceptions that should NOT be cut back in Autumn are illustrated below:
    5. Eriophorum angustifolium and Equisetum scirpoides should not be cut back even in Spring but the others in the images above can have the dead stalks removed when you see the young shoots appearing.
    6. Reduce low growing foliage - all old waterlily leaves & stems and trim some very long stems from rafting plants if outgrown their space - not Potentilla palustris.
    7. Remove small amounts of accumulated silt by dragging a fine mesh net over the pond base.

You will get less algae bloom and blanketweed next Spring:

  • If you clean out your pond little and often
  • Remove all dying plant growth every Autumn to avoid rotting in Winter
  • Do not allow a compost heap to build up on the base.
  • Tidy the pond and remove excess plant growth.
  • Reduce clump size of rafting stemmed plants but do not cut back completely. (In Autumn Myosotis scorpioides has black stems under the water. This plant is not dead - new shoots will appear from this black stem next Spring.)
  • This allows maximum amounts of light to pass through the water to the submerged oxygenating plants in Winter.
  • Leave all oxygenating plants in the pond in Autumn.
  • You will get less algae bloom and blanketweed next Spring.


See below an 8ftx8ft pond: Photo after one season's growth on LHS and after pond clean & cutting back in Autumn maintenance on RHS.

Take special care when you clean and maintain the pond in Autumn:

  • Be aware of any banned invasive plants in your pond.
  • Check out our images on the Banned invasive pond plants page to identify all banned plants.
  • Compost these carefully and never throw into natural waterways.

A smelly pond needs extra attention:

  • This pond will have leaves & other plant growth or excess fish food sunk to the base of the pond
  • The smell is from the layer of silt/sludge at the bottom of the pond resembling your compost heap!
  • Caused by incomplete rotting of vegetation due to a lack of oxygen (anaerobic).
  • If there is too much rotting and not enough oxygen in the water the rotting process (the Nitrogen Cycle) cannot complete.
  • The result is a production of gases - methane and hydrogen sulphide (the smell of rotten eggs)
  • These gases are deadly to fish and other living organisms.

To clean some of the pond base in Autumn:

  • Remove the thick silt layer
  • In a small pond use a fine, flat-edged dipping net which you can drag across the base of the pond and lift any silt into a wheelbarrow for redistribution on the veg patch as a good source of nutrients.
  • Leave some silt for wildlife to hide in and as a source of nutrient for waterlilies next year.
  • Do not be paranoid – you do not need to remove all the silt – look out for dragonfly and damselfly larvae using it as a hiding place and for other overwintering creatures like Great Diving Beetles.
  • We recommend you net across one half of the pond floor one year and the other half the following year.

Alternatively, use Mud Muncher.

  • An environmentally friendly solution to the build up of sludge and mud in ponds.
  • A blend of live bacteria that contains no herbicides or pesticides.
  • It digests organic matter such as fish waste, fallen leaves and decaying plant matter. These all cause the build up of sludge.
  • Helps eliminate odours and reduces the need to clean out ponds and filters.
  • Safe for fish, wildlife, pets and plants in the pond.

Major pond clean and maintenance:

  • Do any major clean out or overhaul an old, neglected pond in Autumn
  • Fewer wildlife species are in the water at that time of year.
  • Be vigilant to check and replace any creatures that are removed from the water accidentally.
  • Place creatures in a bucket of pond water, not tap water, until they are returned to the pond.
  • Remove overgrown plants and decide how much of the clump should go back
  • Would that plant benefit from being divided and potted into more than one basket? See our page Plant propagation
  • Keep as much mature water as possible in clean dustbins to replace back into the pond after the clean out
  • Top up with rainwater over Winter if possible.

Other Autumn pond tasks:

  1. Place any Half Hardy and Non Hardy plants into a greenhouse for protection.
  2. Place all waterlilies low enough in the water to be below any expected ice level in your area.
  3. Check any plants for duckweed and wash them clean before replacing them in the pond.
  4. Check for leaks or splits and weak spots in the pond liner and mend or add a patch of pond liner with waterproof adhesive

Spend more time now and see beneficial results next Spring.

  • Useful long armed pond gloves to clean and maintain the pond in Autumn
  • Cover the entire hand and arm in waterproof materials
  • Either choose Small hand (size 8) or  the larger hand size option
  • No excuses! Clean out your pond now.

For related products - see below: