A small pond is the single most effective thing you can add to a garden for wildlife. Even a metre-wide basin sunk into a sunny border will pull in frogs, newts, dragonflies and hoverflies, give bees somewhere to drink, and offer foxes a reliable water source in dry spells. It needs no pump, no filter and not a single goldfish. It needs the right spot, a decent liner, a few native plants and some patience while it finds its own balance.

Start with the site, not the liner

Most pond failures are siting failures. Before you dig, watch the garden for a few days and note where the sun falls. A pond that gets sun for at least half the day will be warmer and livelier, with more insect activity and stronger plant growth. A little afternoon shade helps in a hot, south-facing garden because it slows evaporation, but full shade keeps the water cold and the plants sulk.

Avoid the drip line of big deciduous trees. Fallen leaves rot down and feed algae, roots can puncture a liner, and the ground is usually dry and matted with roots. Keep the pond away from where you walk at night, and if there are toddlers about, plan for the water to be visible and easy to fence rather than tucked behind a shed.

Foxes visit ponds to drink, often at dusk. Leave a route from the water to a hedge or shrubby corner so anything drinking there has cover close by.

Size, shape and depth

A pond of 1.2 to 2 metres across is generous enough for most gardens and still manageable. Within that, aim for variety rather than a uniform basin:

• One section 60–75cm deep, where amphibians can overwinter and the water stays cool in summer.
• A shallow shelf 10–20cm deep along at least one side, for marginal plants and for bees to land on.
• Gently sloping sides rather than near-vertical walls, so anything that falls in can walk out.
• A wavy outline. Curves and bays create sheltered pockets and look less like a hole in the ground.

If small children use the garden, a broad shallow design is easier to see and safer than a narrow, deep one.

Lining, filling and edging

A flexible butyl or EPDM liner lasts for decades and lets you choose any shape. A rigid preformed pond is quicker to fit but limits your design and usually comes with steep sides.

1. Mark the outline with a rope or hosepipe laid on the ground.
2. Lift the turves and keep them, along with the topsoil; both are useful for edging and for a boggy planting margin.
3. Dig the shelf and the deep section, then check the levels with a long straight plank and a spirit level.
4. Line the hole with sand, then fleece or old carpet, then the liner. Pick out sharp stones first.
5. Fill with rainwater from a water butt where you can. Tap water contains chlorine and chloramine, so if you must use it, let it stand for a few days and let the pond settle for a few weeks before planting.
6. Trim the liner, leaving a generous 30cm overlap all round, and fold it under stones, turf or logs. Liner left exposed to sun perishes quickly.

A pebble beach at one corner — a gentle ramp of stones laid into the water — gives bees and birds somewhere to land and drink without drowning.

Make the edges work for wildlife

Do not ring the pond with steep paving. Frogs, hedgehogs and beetles all need to reach the water and climb out again. A plank laid from the ground onto the shallow shelf, a stack of stones forming a ramp, or simply a sloping edge will save lives.

Never stretch netting over a pond to keep out herons or cats. It catches birds, hedgehogs, grass snakes and frogs, and the wildlife a pond attracts is usually the whole point. Floating plants and a sloping side do the same job without casualties.

Foxes may drink, wade or dig about the margins, especially in dry spells. That is normal, and it is a sign the pond is doing its job. Keep the edge irregular and avoid fragile, expensive planting right at the waterline.

Plant in layers

A pond plants itself in time, but you can speed it up and keep algae in check by working in three layers:

• Marginals around the edge: marsh marigold, water mint, ragged robin, purple loosestrife, soft rush.
• Oxygenators, fully submerged: hornwort, water starwort, common water crowfoot.
• Floaters: a small water lily for shade, plus frogbit in a larger pond.

Buy from a nursery selling native stock and read the labels before you plant. Some non-native pond plants are invasive, a few are banned from sale or from being planted in the wild, and they can escape a garden pond in a flood. Parrot's feather, floating pennywort and water fern are ones to refuse.

Plant into baskets of loam-based compost rather than multipurpose compost, which is too rich and feeds algae. Top the baskets with gravel so the soil stays put when birds and foxes disturb the margins.

Expect green water, and leave it alone

New ponds go green. For the first season the water can look like pea soup, and you will be tempted to fix it. Don't. Chemicals kill the invertebrates that would have cleaned the pond for you, and a pump and filter are unnecessary in a small wildlife pond. Plant more marginals and oxygenators instead, and let them shade the surface. Within a season or two, water fleas, beetles, dragonfly larvae and newts will move in and the water will clear on its own. Do not add fish: they eat tadpoles and larvae, and they turn clear water cloudy.

The maintenance that actually matters

Once the pond has settled, the work is mostly thinning in late summer and doing nothing at all in spring.

• Thin oxygenators in summer if they fill the water column, but leave plenty for cover.
• Skim duckweed with a net now and then, without chasing every last leaf.
• Leave the pond alone in spring. That is when frogs, newts and insects breed, and a tidy-up will wipe them out.
• In autumn, cut back tall marginals but leave the seedheads for birds, and rest cuttings on the bank overnight so anything that crawled out can crawl back.
• Top up with rainwater in dry spells, and never empty and scrub the pond.

If the surface freezes, don't smash the ice. The shock travels through the water and can harm frogs and newts resting in the mud below. Rest a pan of hot water on the surface until a gap melts instead. Where young children use the garden, plan for supervision and a removable fence, and keep the shallow shelf wide rather than deep.

Then step back and leave it slightly untidy. The pond with a mossy log at one end and a few leaves in the shallows is the one that foxes, bees and amphibians will actually use.

Photo: Maria Mileta / Pexels