As with any garden features, the garden pond and its inhabitants need regular attention if they’re to look their best. Pond maintenance needn’t be an intimidating task. It is generally quite minimal but must be carried out regularly if major problems are to be avoided.

First let me state that it is a fallacy to believe that a pond must be cleaned out every spring. In fact, if disturbed too often a healthy balanced pond with clear water may not be achieved. A thorough spring clean should only be necessary every five years or so. Otherwise it should be merely a case of lifting and dividing any overgrown plants and replanting them in fresh compost. Fishing out any visible leaves with a net will help as well.

When it is necessary to completely clean out your pond, this will be made obvious by a large build up of organic debris on the floor or the pond and you will probably be finding it more difficult than usual to keep the water clear. An oily scum may even be seen on the surface. Plants will quite likely be looking overcrowded and merely lifting and subdividing would not be sufficient to put things right.

Emptying a pond.
Before spring cleaning can begin the pool must be emptied of course. This will probably mean siphoning or bailing out the water. Siphoning presents no problem if some of the surrounding ground is lower than the pond. A length of hose is filled with water and with one end submerged in the pond with your thumb over it   the other end is simultaneously removed to a lower area. As long as this is done in sequence and the end of the hosepipe outside the pool is lower than that in the pond, gravity will do the rest. Of course if you have a pump in the pond, then you may be able to use this to pump the water straight into a nearby drain. Always make sure that no small fish or other wildlife can be sucked into the hose. I usually tie a piece of onion or garlic netting over the end.

If the pond has been constructed in the lower part of the garden and this is impossible, then I’m afraid the water will have to be bailed out with a bucket. Great care must be taken to ensure that no fish or other wildlife is removed and discarded. Most fish will linger in the mud and debris on the pond floor and are then easily captured. Whilst emptying, always have a couple of buckets of water ready to accommodate fish.

Fish that have been removed should be placed in as cool a place as possible while spring cleaning takes place. Do not leave the bucket standing in the sun. If a spring clean is likely to take more than just the day then more suitable accommodation will have to be found. A paddling pool is useful here but again keep it in the shade and aerate it if possible. Whichever method you use, do not put fish in clean tap water. There is too much chlorine in it which can kill your fish. If possible use some of te old pond water. Also remember to feed your fish during this time as there will be no natural food source available to them.

Aquatic plants also need to be looked after during the clean especially submerged types. These dry out very quickly when exposed to air. Keep the best plants in buckets of water in a cool light place. When ready for replanting they can be bunched up as cuttings fastened together with the weight or a short piece of wire. Water lilies will last for several days merely wrapped in a generous sheet of polythene whilst marginal plants are mostly happy for a week or so if kept in the call light place. Some submerged foliage might shrivel however the plants will not really suffer.

Dividing plants

On years where a full spring clean is unnecessary, merely tidy up and split the plants where needed. There may be replacements to be made for losses sustained during winter and of course some plants will need lifting and dividing if they are to retain their vigour. As a rule marginal plants should be lifted and divided every two or three years but I wouldn’t try to lift large numbers of plants at one time. This can lead to “fat” and “lean” years as newly replanted aquatics always look rather sparse early on, but conversely if they all need dividing together, by the time this is necessary the whole pond looks overcrowded. The policy of lifting certain groups of plants each year is the most sensible and ensures an acceptable appearance throughout.

Water lilies do not need attention so often. The third year after planting is the best time to divide rigorous varieties, while some of the more restrained kinds will last for four or five years without attention. The need for division should be apparent in any case as the plants will make a preponderance of small leafy growths in the centre of the clump often accompanied by diminishing flower size.

Submerged plants can often be left for a number of years without attention, although the stringy winter growth of semi evergreen kinds like the curled pond weed should be removed each spring to allow fresh growth to break from the bottom. If a new basket of submerged plants is not prospering it is a good idea to shake out the soil and replant healthy young cuttings in fresh compost

When dividing marginal plants treat them rather like herbaceous perennials. Separate tough roots by inserting a couple of hand forks back-to-back. Now lever them apart. Always replant material from the outer edge of the clump as this is young and vigorous.

Water lilies can be treated similarly, except that most will need to be separated with a knife and therefore care should be taken to see that any wounds are dressed with powdered charcoal to prevent infection. The crown of a healthy mature water lily consists of one fleshy root, which was the one originally planted, together with a number of side branches. It is these side growths that should be retained as they are young and vigorous. The original crown is discarded and each severed branch will produce a plant provided it is a healthy terminal shoot.

When you have completed all of the cleaning out, refill the pond. Remember, fresh tap water is not good for your fish. It contains chlorine. This will attack and maybe rot the fish’s gills and may well kill them. Always allow a couple of days at least for the water to settle. Chlorine will evaporate off of the water in time. This can be accelerated by aeration and movement of the water so turn on any pumps and waterfalls. Another reason not to re-stock straight away is that the temperature may be very different from that in which your fish are in. Tap water is usually very cold yet the temporary home holding your fish will have had time to warm up. A sudden change in temperature like this will not do your fish any favours and again could even kill them.