A Small Pond Makes a Big Difference

British amphibians are having a hard time of it. Loss of ponds, drainage of wetlands and tidy gardening have all taken their toll, and species such as the common frog and smooth newt now depend heavily on ordinary garden ponds. A modest pool in a suburban garden can act as a stepping stone between larger habitats, allowing frogs, toads and newts to move through the landscape. Add dragonflies and damselflies, and a well-designed pond quickly becomes the busiest corner of the garden.

The good news is that you do not need much space or money. A pond of around 1.5 to 2 metres across, with gently sloping sides and plenty of native plants, will support far more wildlife than a formal, steep-sided water feature. The trick is to think like an amphibian: they need shallow water to breed in, safe edges to climb out on, damp cover nearby and water that stays clean.

Choosing the Right Spot and Size

Position matters more than perfect construction. Aim for a spot that gets a few hours of sun each day but is not in full sun all afternoon, as warmth encourages dragonflies and helps plants grow, while some shade keeps the water from overheating and algae from running riot. Keep the pond away from overhanging trees, which drop leaves and fruit that rot down and sap oxygen, and avoid the lowest corner of the garden where runoff from paths and driveways can carry pollutants in.

For depth, a good rule of thumb is:

• A shallow shelf around the edge, roughly 20 to 30 centimetres deep, for marginal plants and easy access.
• A deeper central area of 60 to 100 centimetres, which gives amphibians somewhere to overwinter and stops the pond freezing solid.
• At least one gently sloping side, rather than vertical walls all round.

Preformed liners are quick and simple, while flexible butyl liners with a soft underlay suit odd shapes and larger ponds. Fill the pond with rainwater from a butt if you can. Tap water contains treatments that do not trouble people but are best avoided in a wildlife pond, so let it stand for a few days if you have no alternative. Then be patient: leave the water to settle for two or three weeks before planting.

Designing Edges That Amphibians Can Use

Amphibians are surprisingly poor at climbing, and a steep, slippery liner edge can trap them. Creating at least one "beach" of pebbles or gravel that slopes gradually into the water gives frogs and newts a natural exit. A piece of rough log or a few flat stones arranged as a ramp will do the same job and double as a basking spot for dragonflies.

• Leave a strip of long grass, moss and damp leaf litter around part of the margin instead of paving right up to the water.
• Build a small log pile or stone mound a metre or two back from the edge as daytime shelter.
• Avoid netting over the pond and keep the water level topped up so the beach stays usable.
• Skip the fish. Goldfish and koi eat spawn and tadpoles, and they stir up sediment that clouds the water.

Native Plants to Grow and Ones to Avoid

Plants do the heavy lifting in a wildlife pond. They oxygenate the water, provide cover for tadpoles and newt larvae, and give dragonfly nymphs somewhere to hunt. Choose British natives where you can, and plant in baskets of ordinary garden soil rather than rich compost, which leaks nutrients into the water.

• Marginals: marsh marigold, water mint, brooklime, water forget-me-not, lesser spearwort, purple loosestrife and yellow flag iris.
• Submerged oxygenators: hornwort and native water crowfoot.
• Floating plants: frogbit and a small native water lily for shade.

Please avoid invasive non-natives such as floating pennywort, New Zealand pigmyweed, parrot's feather and water fern. They spread rapidly, are illegal to plant in the wild and can smother a small pond within a season.

Keeping the Pond Healthy Through the Year

Once established, a wildlife pond needs very little from you. Never use pesticides, fertilisers or algaecides anywhere near it. Resist the urge to clean it out in spring, which is peak breeding time; if the pond silts up, thin out plants and remove a little sludge in late summer or early autumn instead. Sweep fallen leaves off the surface before they sink, and top up with rainwater during dry spells.

In winter, a pond that is 60 centimetres or more deep will usually stay unfrozen at the bottom. If ice does form, rest a hot saucepan on the surface to melt a hole, or float a small ball to keep a gap open. Never smash the ice, as the shock can harm amphibians resting below.

What You Might See, and When

Common frogs usually arrive to spawn in February and March, leaving clumps of jelly in the shallows. Smooth and palmate newts follow in spring, and you may spot them returning to the pond on damp evenings. Dragonfly and damselfly nymphs live underwater for a year or more before climbing emergent stems to emerge as adults between late spring and late summer.

Give it time. A new pond often looks lifeless for a few weeks, then fills with insects, and amphibians usually find it within one or two breeding seasons. Once they do, the small stretch of water you created quietly becomes one of the most valuable habitats in the neighbourhood.