Making a Wildlife Pond in a Small Garden

Why a small pond is worth the dig

A pond the size of a dining table will pull in more wildlife than almost anything else you can do with the same square metre. Frogs, smooth newts, water beetles, damselflies, hoverflies and a steady traffic of birds coming to drink and bathe will all find a basin just 1.5 metres across, provided the shape is right. The secret is not volume but access: gentle slopes so creatures can get in and out, a shallow beach for drinking and bathing, and a rim crowded with native plants. Add no fish at all — they eat everything that moves — and the invertebrate life will thrive.

Choosing the site

Aim for at least half a day of sun. Warmth drives the insect life that makes the pond feel alive, and a pond in deep shade tends to sit cold and lifeless. That said, a little dappled shade at midday in July is a bonus, as it keeps the water cooler and slows evaporation.

• Keep clear of big trees and shrubs — roots puncture liners and autumn leaf fall feeds the water into a green soup.
• Site it where you can see it from a window or a favourite chair. You will watch it far more than you expect.
• Leave the surrounding ground rough. Long grass, a log pile and a few stones at the edge give amphibians somewhere to hide when they leave the water.
• Think about the view from below as well: raised ground or a slight mound beside the pond makes an easy basking spot for frogs and newts.

Digging: shape, depth and the shallow beach

Mark out a soft-edged shape with a hosepipe — kidneys and ovals look more natural than circles. A pond of roughly 1.5 by 2 metres is generous for a small garden; even 1 by 1.5 metres works if the profile is right.

Dig in tiers rather than a bucket-shaped hole. Work down to a marginal shelf about 20 to 25 centimetres deep and at least 25 centimetres wide around most of the perimeter, then a central area 45 to 60 centimetres deep. That depth is enough to keep the water cool and give frogs somewhere to overwinter in the silt, without making the pond hard to build.

Then the part most people skip: a beach. At one end, cut a gentle ramp — no steeper than one in three, shallower if you can — sloping from dry ground down into the water. Line it with small round pebbles and a few larger flat stones wedged in place. Hedgehogs, birds, bees and frogs will all use it, and it stops anything from becoming trapped.

Lining and filling

Butyl or EPDM rubber is the most reliable choice; a 0.75 to 1 millimetre butyl liner will outlast most of us. Buy more than you measure: you want at least 30 centimetres of overlap all round plus the depth, so a 1.5 by 2 metre pond with a 60 centimetre centre typically needs a piece around 3 by 3.5 metres.

• Line the hole with old carpet, sand or a proper geotextile underlay. This protects the liner from stones and roots and is not a step to skip.
• Lay the liner loosely, tucking pleats rather than stretching it, and weight the edges with turf or stones temporarily.
• Fill with rainwater from a butt. Tap water contains nutrients and chlorine; if you must use it, let it stand for a few days or treat it, and accept an algae flush in the first season.
• Trim the liner once the pond is full and the weight has settled it into shape, leaving a good 20 centimetres to fold under the edging.

Hide the liner rim with turf, log slices or stones, but keep some bare ground around the edge — amphibians prefer to walk out onto soil and moss rather than gravel.

Planting for wildlife

Plant in spring or early summer, using baskets of ordinary loam with no fertiliser. Fertiliser feeds algae, not the plants you want.

• Marginals: water forget-me-not, marsh marigold, brooklime, water mint, lesser spearwort and ragged robin.
• Oxygenators: hornwort and water starwort — the best spawning cover for frogs and newts.
• Floating: frogbit, or the miniature waterlily Nymphaea pygmaea 'Helvola' if you have room for one.
• Avoid: yellow flag iris, bulrushes and floating pennywort in a small pond. They are thugs, and the last is invasive.

Looking after it

Resist the urge to intervene. A new pond usually goes green for a few weeks, then clears as plants and grazing invertebrates find their balance. Never introduce frogspawn or plants from another pond — disease and invasive species travel with them, and amphibians will arrive on their own within a season or two.

• Twirl blanketweed out with a stick in late spring, then leave it on the edge overnight so anything caught can crawl back.
• Net out excess leaves in autumn, but leave the bottom silty and undisturbed — that is where frogs and newts spend the winter.
• Top up in dry spells with rainwater, and keep a shallow dish of water on the ground nearby for hedgehogs.
• Cut back dead stems in early spring, not autumn, so insects can overwinter in the hollows.

Keep it chemical-free, leave the edges a little untidy, and within a year you will have dragonflies hunting over a pond you can cross in one step.