Pond Plant Maintenance Guide

Winter Pond Plant Maintenance Guide

Early winter

Ponds should not be allowed to ice over, because the ice layer prevents oxygen from getting in to the water as well as harmful gases being allowed to escape. But what should you do if your pond does ice over? NEVER crack ice with a hammer. This can be deadly to fish; the shockwaves and reverberation can stun or even kill. Melt a hole with a saucepan full of boiling water. If the ice is more than 1 cm (½ in) thick, it can take five minutes or more to melt the hole. It will need to be repeated the following day!

To prevent ice from forming, install an electric pool heater. It comprises a straight rod element fitted through a wooden or polystyrene float that keeps the heater at surface level. Plug it in to the mains supply and leave it in position whenever hard frost is forecast. Alternatively, keep a section of the pond ice-free by running a fountain or waterfall permanently. The moving water does not become still enough for ice to form.

Water hyacinth

Water hyacinth (Photo credit: Wikipedia)


Tender pond plants (such as Eichhornia, the water hyacinth) that are lifted in autumn for storing indoors should be inspected regularly. Sometimes, misting over the tops of the plants is all that they require; otherwise, water them.

 Many people stop feeding fish in winter, while others believe that if the weather is mild and the fish are active, their reserves will be depleted if they do not eat. If the fish are swimming close to the surface, it is a good idea to offer them a sprinkling of food. If they take it they can have a little more; if they decline, then stop.

Late winter

 If you are thinking about making a new pond, or reshaping or enlarging an existing one, this is a good time to do it. If the work is completed now, you will be able to start planting, and introducing fish in about six weeks, which will bring you nicely into the early to mid-spring season.

This is the time of year when frogs are mating — and there will be an abundance of frog spawn and tadpoles in your pond as a result. It is important to ensure that any frogs, toads and newts can leave the pond when they need to. Make sure there is a small ramp which these creatures can use to escape.

Spring Pond Plant Maintenance Guide

Early spring

Remove pond algae as and when you see it. It will only flourish if left unchecked. Also, decaying vegetation will pollute the water and harm the fish.

With their resistance to infections at its lowest, fish need careful nurturing to restore their normal strength and energy and to improve their health generally in time for the breeding season. Thus, it is important to start feeding them, but do not use too much food or it will contaminate the water.

Other jobs for early spring:

If you take your submersible pump out of the pond for the winter, now is the time to re-install it.

Test the quality and pH of the water, and make any remedial treatments.

Feed containerized aquatic plants with appropriate pellets; feed established bog garden plants with general fertilizer, but do not allow any run-off to enter the pond.

Lift and divide overgrown marginals.

Plant new plants in the bog garden.


Give bog garden plants a little extra feed now but always use fertilizers with caution near a pond. When there is no wind, sprinkle a handful of fish, blood and bone powder around the base of the plants, rather than spraying liquid feed over them. Some plants may need staking at this time.

Other water garden jobs for mid-spring:

Introduce new aquatic plants to your pond.

Divide overgrown waterlily clumps.

Make efforts to rid your pond of algae and blanket weed — this is when it can be at its worst.

Check for signs of slugs on bog garden plants and marginals, and treat as appropriate.

Late spring

Tidy the bog garden and remove any dead or diseased foliage. Plants that have finished flowering — such as forget-me-nots — may now be affected by mildew. Cut the affected parts hard back. Deadheading is important. Apart from making the plant less ugly it also removes any places where mould can set in. Never forget that by its nature a bog garden is damp all of the time and botrytis, grey mould and similar diseases may be more troublesome here than elsewhere in the garden.

If your pond fish have spawned, make sure that the fry have access to a shallow area, safe from the attentions of adult fish that will consider them tasty morsels.

Other water garden jobs for late spring:

Check for signs of plant pests, such as aphids, and treat as appropriate.

Limit the spread of duckweed at this time, otherwise by the end of summer your pond could be covered.

Summer Pond Plant Maintenance Guide

Early summer

It is surprising how much water can be lost through evaporation on a really hot day, particularly with small features such as water barrels or wall-mounted fountains. Keep the water level topped up regularly; by far the easiest way to do this is with a hose. Make sure that you have a fine-spray attachment, or the pool will be churned up and plants disturbed.

In hot weather the water becomes comparatively warm and the fish can become lethargic. Feeding should be reduced slightly during these periods.

Other water garden jobs for early summer:

Thin out overgrown clumps of oxygenators and other fast-growing aquatics.

Weed the bog garden, and apply copious amounts of water during dry spells.

Check and cut back overgrown waterlilies.


Life in the pond will not come to a grinding halt if you are away, but there are a few things you should do before you go: Ask a neighbour to switch on any aeration device (I.e. a fountain or a waterfall/cascade) for a short while during the period you are away. This will help to oxygenate the water. If you do not have a powered aeration device, tell your neighbour that emptying a bucket of clean water, or running a hosepipe into the pond on muggy days, will do some good. As long as there are plenty of water plants of all kinds in your pond, fish can generally manage well enough for a couple of weeks without supplementary feeding. Block feeders are available for fish in ponds that have few plants.

Other water garden jobs for mid-summer:

Pond levels may still need topping up in warm weather.

Continue to remove blanket weed and other forms of algae from the pond water.

Late summer

This is when you should start a weekly routine of pulling out dead leaves and stems from your pond, before they sink to the bottom and give off harmful gases.

Your weekly tidying regime should be as follows:

Cut and clear away any collapsing stems and leaves before they enter the water.

Trim back fading marginal plants by two-thirds.

Leave one or two areas as cover for the various water animals that spend their winter hiding near the banks.

Remove older leaves of waterlilies.

Watch for the two main waterlily pests: aphids and lily beetle. The aphids (blackfly and greenfly) are instantly recognisable. The beetles are brown and small, and they eat holes in and on the edges of the leaves. Fire a jet of water at the leaves to knock the pests in to the water, and remove the worst affected leaves.

Other water garden jobs for late summer:

Divide overgrown marginal plants before the soil and water are too cold for replanting.

Detach young portions of tender aquatic plants (such as the water hyacinth, Eichhornia) for overwintering safely indoors.

Tropical or tender fish that have been enjoying the summer outdoors should be returned to their winter quarters indoors.

Autumn Pond Plant Maintenance Guide

Early autumn

Lift and divide any bog garden plants that need it — except the tenderest types, which are better left until spring. Pull apart large clumps and discard the tough older centres, replanting only the more vigorous, outer sections. Leave waterlilies and other fully aquatic species until spring.

Cut back clumps of marginal species. Leave long stumps, especially if they are a trifle tender and have hollow stems. The accumulation of water within the stem bases, which will freeze during winter, can cause damage and allow rot to penetrate the crown.

Continue to feed fish regularly, but it is even more important from now on that you make sure they eat all that is given to them. Excess food will drop to the bottom and rot, so scatter a few flakes or pellets and supply more only if the first are completely devoured.


If you prefer to remove the pump and store it over winter, then now is the time to disconnect it. Clean it out as best you can, as well as the associated pipe-work.

Continue to collect leaves from the pond or water feature. The further we go into autumn, the greater the likelihood that ignored leaves will sink to the bottom of the pond, so be prepared to delve into the depths. Try not to disturb the mud too much — many creatures will be hibernating in it.

Other water garden jobs for mid-autumn:

Continue to remove blanket weed and other forms of pond algae

As daylight lengths shorten, thin floating plants (such as duckweed and Azolla), to allow as much sunlight on to the pond as possible.

Late autumn

This is a good time for building new ponds (or extensions to existing ones), free from the urgency of spring, the heat and dryness of summer and the cold and inhospitable ground conditions of winter. The weather now is usually warm enough to make the work pleasant, while the risk of prolonged frost is still slight.

Around now the water in the pond will finally reach 5°C (41°F), the critical point below which all feeding of fish should stop.

Other water garden jobs for late autumn:

Check your liner (or concrete) above the waterline for cracks and leaks.

Check for slippery paths and paving stones around the edge of the pond — these can be lethal.

Prevent ice forming.

10. April 2012 by Dave Pinkney
Categories: Water Garden Plants | Tags: | Comments Off on Pond Plant Maintenance Guide


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