Why a small pond earns its place

You do not need a half-acre of water to make a real difference. Even a pond the size of a dining table will pull in wildlife from gardens several doors away, because water is the one thing most plots are missing. Frogs, toads and newts arrive first, often within a season. Then come the insects: damselflies, dragonflies, water beetles, pond skaters and hoverflies. Birds will use the shallow edges for drinking and bathing, and hedgehogs will visit for a drink on dry summer nights.

What matters more than size is the variety of edges you create. A pond with a shallow shelf, a deeper middle and a gently sloping beach is a far richer habitat than a steep-sided bucket of water. Aim for structural variety rather than volume, and you will get far more for your effort.

Choosing the right spot

Sunlight is the single biggest factor. Pick a spot that gets at least six hours of direct sun in summer, as warmth drives plant growth, insect activity and frog spawn development. A pond shaded all day will sulk and stay lifeless.

Beyond light, check these practical points:

• Keep clear of large trees. Falling leaves rot and deoxygenate the water, and roots can puncture a liner.
• Choose ground that is reasonably level, or has a gentle fall you can work with.
• Position it where you can see it from the house. A pond you watch daily gets noticed and cared for.
• Site it near a hedge, log pile or long grass so amphibians have cover to travel through.
• Avoid the lowest point of the garden if it floods, and keep it away from where toddlers play unsupervised.

Shape, depth and safe access

Aim for roughly two metres by one and a half if space allows, though smaller is still worthwhile. Dig a deeper section of 60 to 75cm so frogs and newts can overwinter in the mud below the frost line, with at least one shallow shelf at 20 to 30cm for marginal plants and for creatures to haul themselves out.

The most important design rule is the slope. Vertical sides drown wildlife and trap hedgehogs. Give one entire side a gentle ramp, and add a few extra escape routes:

• A pebble beach that runs gradually from dry ground into the water.
• A half-submerged log or a piece of stone, angled so it breaks the surface.
• A shallow boggy margin where damp-loving plants can soften the edge.
• An irregular, curvy outline rather than a neat circle, which creates sheltered pockets.

If you have small children, a shallow beach at one end is both a safety feature and excellent wildlife habitat.

Digging, lining and filling

Mark the outline with a length of rope or a hose, then strip the turf and set it aside upside down to use later. Dig your shelves and deep section, checking as you go that the rim is dead level all the way round. A rim that is 2cm out will show, so use a spirit level and a long straight edge.

Line the hole with old carpet, sand or a proper geotextile underlay, then lay butyl or EPDM liner, which will last twenty years or more. Leave a 30cm overhang all round while you fill, then trim and tuck it under turf or paving, sitting the finished edge about 5cm above soil level to stop run-off washing in.

Fill with rainwater from a water butt if you can. Tap water is fine in the UK once the chlorine dissipates, but rainwater is free, soft and better for plants. Let the pond settle for a week or two before planting, and expect it to look cloudy at first.

Planting it up with natives

Native plants support far more insect life than exotic ones, and they suit our climate. Work in three layers:

• Oxygenators: hornwort, water starwort and water milfoil, which keep the water clear and provide cover for tadpoles.
• Marginlas: marsh marigold, water forget-me-not, brooklime, lesser spearwort, ragged robin and yellow flag iris. Keep vigorous iris in a basket.
• Surface cover: a dwarf water lily in a basket, whose leaves give shade and landing pads for emerging damselflies.

Plant in baskets of hessian-lined subsoil and grit to avoid clouding the water, and cover the surface with gravel. Never introduce floating pennywort, water fern, parrot's feather or New Zealand pigmyweed — they are invasive and illegal to plant in the wild. Resist putting in fish; they eat everything that makes a pond interesting.

Looking after it through the year

A wildlife pond needs less fuss than you might think. Top it up with rainwater in dry spells rather than tap water, and never empty and scrub it. Twice a summer, twirl excess blanketweed out with a stick and leave it on the side overnight so trapped creatures can crawl back.

Thin overcrowded plants in late summer, and cut back the margins in early spring, leaving some hollow stems standing for insects. In winter, do not break ice by force, as the shock can kill frogs resting below — rest a pan of hot water on the surface instead. Do that much and your small pond will reward you for years.