Why a Pond Is the Best Thing You Can Add to a Wildlife Garden

If you only do one thing for wildlife this year, make it a pond. Even a modest one — a sunken half-barrel, an old washing-up bowl, a two-metre puddle lined with butyl — supports more species per square metre than a wildflower meadow or a native hedge. It is the single quickest way to turn a quiet garden into a busy one.

Within weeks of filling, pond skaters and water boatmen will arrive on their own. Frogs generally find new water within a season; smooth and palmate newts follow. Dragonflies and damselflies will hunt over the surface and, if you plant the edges properly, lay eggs that hatch into larvae in the silt. Add bathing sparrows, drinking hedgehogs and hunting bats, and you have a habitat that works day and night.

Amphibians have suffered badly in the British countryside over the last fifty years, with the loss of field ponds and the drainage of wet ground. Garden ponds are now a genuine stronghold. Your small patch of water matters more than you would think.

Choosing the Spot

Ponds like light. Aim for around four to six hours of direct sun each day — enough to warm the water and encourage dragonflies, but with some afternoon shade to keep algae in check. Full sun all day encourages green water; deep shade discourages almost everything.

• Keep clear of overhanging deciduous trees. Falling leaves rot down and feed the algae you are trying to avoid.
• Choose level ground so the liner sits evenly and the edges do not show.
• Leave access on at least one side so you can reach in with a rake, and so you can watch what turns up.
• If young children use the garden, build in a shallow shelf along one edge or lay a sturdy metal grid just below the surface. A raised pond with a wide, planted ledge is another good option.

Digging, Lining and Filling

Depth matters. Aim for about 60cm at the lowest point, which keeps water liquid at the bottom through all but the hardest winters and gives frogs somewhere to overwinter in the silt. Anything shallower than 45cm risks freezing solid.

Dig a shelf around part of the perimeter at roughly 20–30cm deep. This is where your marginal plants will sit, and where birds will stand to drink and bathe. Slope one side gently into the water rather than cutting it vertical — that is your wildlife ramp, and it saves you building one later.

Line the hole with a butyl liner over a layer of soft sand or old carpet. Run the liner well past the edges, then tuck it under turf or hide it with stones so it looks settled from day one. Fill from a water butt if you can. Rainwater is soft and low in nutrients. Tap water will do in an emergency, but it carries nitrates and phosphates that feed algae, so use it sparingly. Leave the pond to settle for a fortnight before planting.

Planting in Layers

Think of a pond in three zones: the boggy margin, the shallow shelf, and the open water. Fill all three and the pond will largely look after itself.

• Marginals: marsh marigold, water forget-me-not, water mint, purple loosestrife, yellow flag iris, flowering rush and lesser spearwort.
• Oxygenators: hornwort, water starwort and curled pondweed, which grow below the surface and keep the water clear.
• Floating leaves: a small waterlily or frogbit, which shades the water and gives dragonfly larvae somewhere to climb out.

Plant into baskets of low-nutrient loam topped with gravel — ordinary compost is far too rich and will trigger an algae bloom. Whatever you do, avoid the invasive non-natives that escape from garden ponds: New Zealand pygmyweed, floating pennywort and water fern. They are illegal to plant in the wild and will smother everything.

Small Features That Save Lives

A steep-sided pond is a trap. Hedgehogs, voles and fledgling birds drown in them every summer.

• Leave at least two gentle exits — a sloping turf edge, a rough log, or a stack of stones breaking the surface.
• Keep a shallow beach area where a hedgehog can wade, drink and walk out.
• Build a log pile or stone heap nearby for frogs and newts to shelter in when they leave the water.
• Let a corner of long grass grow up close by. Amphibians need damp cover on land as much as in the pond.
• Do not add fish. Goldfish and sticklebacks will clear out tadpoles, newt larvae and almost everything else within a season.

Looking After It Through the Year

Resist the urge to tidy. A pond is meant to be a little untidy, and the mess is the habitat.

In spring, leave the pond alone. Frogs spawn in February and March, toads trail strings of eggs through the weed, and newts wrap theirs in folded leaves. Anything you pull out now takes next summer's adults with it.

Through summer, top up with rainwater and twirl excess blanketweed out on a stick, but leave some — it shelters larvae and tadpoles.

In autumn, net out fallen leaves before they sink. If you must clear the pond, do it in late October, and leave the debris on the side for a day or two so creatures can crawl back in.

In winter, leave seedheads standing for overwintering invertebrates. If ice forms, never smash it — the shock travels through the water and can kill what is resting below. Sit a pan of hot water on the surface instead, and only if you really need to.

Do all of this and by next spring you will have frogspawn, diving beetles, damselflies drying their wings on the iris tips, and a garden that feels properly alive.