Pond care

Ponds are a lovely addition to any garden and can provide a rich habitat for a range of wildlife. However, without care ponds can soon become an eyesore with overgrown plants, weeds and water that is unhealthy for fish and other wildlife. Occasional cleaning and regular maintenance are required.

Removing blanket weed from a pond. Credit: RHS/Advisory.

Quick facts

Suitable for All garden ponds
Timing Year round
Difficulty Moderate to difficult

Suitable for...

All ponds need regular maintenance to prevent them silting up and turning into bog gardens.

Small ponds need a complete overhaul to remove debris every five years, while large ponds need thorough cleaning every 10 years.

Maintaining your pond

The best time to clean ponds is in late autumn when many creatures are less active.

Pond cleaning

  • Start by preparing a holding tank in a shady spot for fish and deep water plants; use some pond water in the tank, unless it is particularly cloudy. Marginal (water’s edge) plants will survive out of the pond as long as they are kept moist and shaded
  • The easiest way to drain the pond is to use a pump, which can be rented for the day from a machinery hire shop
  • As the water level falls, remove fish as they become visible
  • Remove plants as the water levels drops, placing them in the holding tank. Take the opportunity to re-pot or divide plants if necessary
  • If you find any, put larger pond creatures into the holding tanks
  • Place decaying plant material on the side of the pond, so any smaller creatures hidden away can return to the pond
  • Scoop up the silt from the base. You can use this on your border, but retain a little to add back to the pond as it will help re-establish tiny organisms
  • Clean the liner with a scrubbing brush and water, bailing the dirty water out with a bucket
  • Return the saved silt and any saved pond water. Next, refill with water (rain water if possible), positioning pond plants as you go
  • Finish by returning the fish and any other creatures

After cleaning out the pond, it can take several months or years to return to a balanced ecosystem.

Summer pond care

  • Water evaporates during windy or hot weather, leading to the water level dropping. The reduced surface area can be damaging for fish as there’s less oxygen available, so top up the pond if necessary. Ideally use rainwater from a butt as tap water is rich in nutrients that causes algae to prosper
  • If you do have to use tap water and you keep fish, add the tap water gradually in small amounts to prevent the cold liquid shocking the fish in the pond
  • On hot, humid nights, spray water over the surface of the pool from a hose to break the surface and improve oxygen levels in the water. Alternatively, install or turn on a water feature to keep the surface bubbling gently
  • Floating weeds can quickly cover the surface of a pond if left unchecked, so twirl these out with a stick or use a net to scoop them out. Leave weeds and algae on the side of the pond overnight, so that larger creatures can return to the water. Rinsing the material in a bucket of pond water can help release smaller creatures which can then be returned to the pond

Winter pond care

  • If the pond is stocked with fish and it does freeze over, melt the ice by placing a hot pan on the surface, or install a pond heater or water feature to prevent freezing occurring. Floating a ball on the water in cold weather can also delay freezing. Never smash the ice, as the shock waves can harm fish
  • Improving the oxygen levels in the water by circulating it with a pump benefits both amphibians and fish, particular in deeper ponds where oxygen does not diffuse readily through the water. However, making a hole in the ice is not essential for ponds not stocked with fish
  • Ensure plenty of light gets to the pond by pruning back overhanging branches and brushing off snow. This will allow submerged plants and algae to continue to photosynthesize and replenish oxygen levels in the water. Consider adding more oxygenating plants in the spring if there aren't many

Pond plant care through the seasons

  • Mid-spring through to early summer is the best time to buy pond plants as the water is warming up and plants will respond by growing away rapidly
  • Aim to keep around 50 percent of the surface free of vegetation by thinning out plants occasionally during the summer
  • Deep water aquatics with floating leaves, such as water lilies, benefit from regular dividing and re-potting, carried out in spring. Place containers on raised bricks lowered in stages as the plants grow, so the leaves can always reach the surface until the final depth is reached when the plant is mature
  • If not being potted on, water lilies benefit from a supplementary feed in the spring with a specialist aquatic plant food to encourage better flowering
  • Snip off any tatty leaves, along with any fading flowers in summer. Remove dead leaves and debris from plants early in the autumn to avoid decomposing vegetation building up in the pond
  • Thin out excessive growth of underwater oxygenating plants. Four to five bunches (each containing three to four stems) should be sufficient for each square metre or yard of pond surface area

Problems

In late spring, pond algae and weed growth can be rife. There are various ways of controlling and preventing these problems. If you have a large pond with a serious weed or algal problem, then you may choose to contact a contractor or specialist centre for advice.

Links

Centre for Aquatic Plant Management
National Association of Agricultural Contractors (NAAC)

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  • Dawn chorus avatar

    By Dawn chorus on 27/07/2014

    I have tadpoles in my small pond at present I would like to know if I must have running water to keep the pond clean..I am intending to keep it as a wild garden feature and will not be adding fish ...please advice me how to maintain the pond so that it will attract wild life...thank you ...Vron


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  • Fullywild avatar

    By Fullywild on 19/07/2014

    We inherited a garden pond with 20 or so fish between 8 and 15 inches long. The pond is approx 3m by 2m x 800mm deep. The previous owner had just not done anything to look after it and it was in a bad way. The water surface is free from algae and is not green or anything and a nice leafy floating plant grows well (we keep this cut back to about 1/3 to 1/2 coverage to provide fish shade.) But the water is not clear at all, we can't see the bottom of the pond, which is also very silted up. Have bought a pond vac but it is not making much difference and need to give the pond a good overhaul. The submerged pump seems fine (jetting the water out at a very good rate when disconnected from the filter box) but the water flow from the external filter (and down to the waterfall) is very slow in comparison. We have deduced that it is a new filter that is what we need but are confused as to what is the best way to go with all the options and absolutely no experience. The combined submerged pumps and filters that can run a waterfall - and a fountain - look attractive, but with so many fish do they have enough filter power to be efficient? As the existing submerged pump seems fine, do we need to just buy a new external filter box? Can anyone recommend a good - but not too expensive - external filter that is easy to clean and maintain?


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