GG29

Setting up a pond

A pond is an asset in any garden. It provides a breeding site for amphibians, a home for water dwellers and a bathing and drinking site for thousands of other creatures. A garden pond contributes considerably to the balance and diversity in a successful garden.

Ponds can be any shape or size. It is possible to buy a pre-formed shape, or to create and line your own design, We have chosen to describe a pond style which would suit an urban or rural area, lined with a butyl liner. Good quality butyl is not cheap, but it is easy to use, and lasts around 20-30 years.

Choose the site carefully

Ponds need plenty of sunshine, about 5 hours daily is ideal. This helps the plants to grow and keeps the water warm. A cold dark corner is not a suitable site.

Ponds do not need trees. The roots can disturb, or even pierce, the liner, and the leaves from the trees choke and clog the water in the autumn.

Ponds should be enjoyed, so need to be accessible. Try to provide somewhere to sit, observe and enjoy the life and activity of the pond.

Ponds should be safe. Young children can drown in 8cm (3") of water. Vandals can destroy a pond in moments. Rubbish can contaminate the water and destroy pondlife.

Ponds need to be maintained. Make sure that access is straight forward. Avoid designs or positions that impede easy maintenance.

Timing

Early spring is probably the best time of year for pond installation. This gives wildlife time to discover, colonise it, and settle in before winter. Plants also are best introduced at this time as they too need a season to become established.

Preparing the site

Dig the hole. The size is up to you, whatever fits your garden. A pond has to be at least 60cm deep at one point. This allows wildlife to be safe during prolonged spells of hot or cold weather. It may be deeper, but it should not be shallower. Dig down until you have 60cm, plus extra to allow for the protection required by the pond liner (usually another 10-15cm). The pond should have a shallow, gently sloping area somewhere around the perimeter to allow wildlife to get in and out easily. Shelves are useful, at another point, to stand plant pots on.

This is a good interior cross section
Don't make the outline too ornate. Fitting a liner into lots of curves and angles is awkward. An oval or a pear shape might seem boring, but is easy to install and looks attractive when established.
Take care when disposing of the soil. There will be a lot more than you think. You may well go into sub-soil while digging. This is a different colour (paler) than top soil, and infertile. So avoid mixing it with the top soil. Some people use the top soil to create a rockery at the end of the pond, and the infertile sub-soil for a wildflower meadow.
Remove all stones and other hard objects from the hole. The liner will be protected, but it is wiser to be fussy about clearing the site.
Firm around the base and sides of the dug area. The soil must not cave in when you are placing the liner in position.
Make sure the pond edges are level with each other in all directions. If necessary build up a side to achieve this. Check with a spirit level on a piece of timber.

Adding a soakaway

Some ponds need an overflow arrangement if excess water after continuous heavy rain will flood and cause a problem. An overflow pipe, leading to a soakaway can be installed quite easily.
Protect the liner with firstly a layer of sand, then a layer of carpet or cardboard, or thick layers of newspaper. Purpose-made underlay is sold commercially if these other materials are unavailable. Pond liner sizeSize of liner required = length of pond + depth [depth x 2] by width of pond + [depth x 2]For example, a pond 1m x 40cm will need 100 + (60x2) x 40 + (60x2) = 200 x 140cm.
Lay the pond liner over the hole. Allow about 30-40cms overlap around the edges (see main illustration). Dip it half-way into the hole, but don't try to shape it close to the sides. Weigh down the sides of the liner with heavy stones around the pond edge. If you are going to plant directly into soil, now is the time to put some on the base of the liner. Fill the pond with water. As the weight of the water increases, the butyl will stretch and fit snugly against the sides. For the first ten days or so the pond will look like brown soup. As the soil settles it will clear.
Before adding plants or water creatures to your new pond, wait for 3-4 days. This will allow the water to reach air temperature, and for some of the chemicals to evaporate.

Planted pond

Green water

For one or two days after filling the pond the water will be crystal clear. It will then, almost overnight, become bright green, like pea soup. This green growth is algae, growing as a result of sunlight mixed with nutrients in the water. Don't worry, and don't replace the water. As the water creatures start to feed, and as the plants start to grow, the algae will be starved out. Aim to have about _ of the pond surface covered with plants, and plenty of water snails and water fleas. This combination uses up oxygen and reduces the light the algae needs in order to flourish. In addition, the water creatures eat the algae. You'll see the snails browsing around the sides of the pond, cleaning as they go.

Planting the pond

Ponds should have a wide assortment of plants. This variety provides food and shelter for an extensive range of water-dwelling creatures, and for those creatures who need water without living in it.

Put in:

deep water plants, such as water lilies, Water Crowfoot
emergent plants (needing 15-50cms depth) such as rushes, reeds
marginal plants (needing 15cm depth) such as Iris, Marsh Marigold
floating plants (floating freely) such as Water Soldier.

If you have a boggy area next to the pond then choose plants which can take constant moisture at their roots, such as Primula, Lysimachia, Astilbe. There is a huge range available.

Small ponds should be planted with care. Plant labels need to be checked for growth details. Specialist suppliers have a wider choice and know more about the plants than general garden centres do. Avoid at all costs Canadian Pondweed (Elodea canadensis) and Austrian Swamp Stone Crop (Crassula helmsii or Tillea recurva). They take over.

Plants may be put in pots, and these placed on the bottom and the shelves of the pond. Or you may plant directly into the soil on the base of the liner. The use of pots is probably advisable in a smaller pond, as it keeps plant roots under control. Use mesh pots specially designed for ponds. If you prefer terracotta pots, drill holes in the sides to allow water and roots more movement.

Some plant suggestions

Deep water aquatics
- Water Lilies (Nymphaea) (Note - it is very important to choose the correct size of lily for your pond)
- Water Hawthorn (Aponogeton distachyus) - will tolerate 8-60 cm of water.
- Brandy Bottle Lily (Nuphar lutea) - needs a big pond as it has a large root system.
Marginal Plants

These plants grow in the shallows at the pool edge. Some (not listed) can become very invasive, so choose with care.
- Sweet flag (Acorcus calamus & A. calamus variegatus)
- Marsh Marigold (Caltha species)
- Golden Sedge (Carex stricta :'Bowles Golden')
- Golden buttons (Cotula coronopifolia)
- Iris - many different varieties, colours and sizes
- Lobelia (Lobelia fulgens and L. cardinalis)
- Bog bean (Menyanthes trifoliata)
- Pickerel (Pontederia cordata)
- Japanese Arrowhead (Sagittaria japonica)
- Reed mace (Typha spp) - select the correct size for your pond.
Oxygenators

These submerged plants provide food and shelter for pond life. In addition they absorb minerals and carbon dioxide which helps starve algae and keeps the pond water clean.
- Water Milfoil (Myriophyllum)
- Water Buttercup (Ranunculus aquatilis)
- Hornwort (Ceratophyllum)
- Water Violet (Hottonia)
Floating Plants

Cover on a pond can be created with floating plants alone. Not all varieties are fully hardy.
- Water Soldier (Stratiotes aloides)
- Water Chestnut (Trapa nataus)
- Bladderwort (tricularia Spp)

Watch out for Duckweed (Lemna spp) which often comes with purchased plants. This tiny leaved plant can cover the surface in no time at all. The only way to get rid of it is daily removal until all traces have vanished.

Management

Once established, a pond is fairly self-managing. However, in the autumn, leaves should be removed as they can decompose and cause toxic conditions. A net spread over the surface will prevent them entering the water. As plants grow, they will need to be split and kept to a reasonable size for the pond. Work like this, causing major disturbance, is best done in late summer, after frogs, toads and other creatures have hatched, and before hibernation starts. Any major pond overhaul can take place at this time.

Long spells of hot weather can cause excessive evaporation in a small pond, which will need topping up. Water straight from the tap contains chlorine. Fill a can or two with water and allow to stand for 24 hours to allow the chemicals to evaporate, then add to the pond. A good system is to add the water to the pond in the evening, refill the containers immediately and allow to stand for 24 hours until the next evening.

Weeds can choke a small pond. Remove excessive growth ruthlessly. Do not allow duckweed or blanket weed to take hold. Put piles of weeds by the pond side for a day, or drape them over bamboo canes placed across the pond. Enmeshed pond creatures will crawl, or fall back, into the water.