Creating a Small Wildlife Pond in a Coastal Garden

A small pond is the best wildlife feature you can add by the sea

Coastal gardens can feel like a challenge: thin, sandy or stony soil, salt-laden wind, and long dry spells in the east. Yet freshwater is genuinely scarce in most coastal landscapes, and that scarcity is exactly why a pond works so well here. Every creature within flying distance of your garden — beetles, damselflies, frogs, birds, hedgehogs — is looking for a reliable drink and a place to breed. A pond just 1.5 metres by 1 metre, tucked into a sheltered corner, will attract more wildlife than almost any other change you could make. You do not need a pump, a filter, a fountain or any fish. Still, plant-filled water is the whole point.

Choose a sheltered, sunny spot

Ponds need light, so aim for at least half a day of sun; a pond in deep shade stays cold and lifeless. Wind is the real coastal issue. It dries the surface, drives spray into the water and can salt it, so site the pond behind a hedge, a low wall, a shed or a bank of tough grasses. Avoid the strip directly downwind of the sea if you can manage it. Keep clear of overhanging trees, whose leaves will fill the pond and whose roots can puncture a liner, and avoid any hollow where runoff from the lawn drains in — fertiliser and weedkiller will turn your water green.

Dig shallow, with gentle edges

Small and shallow is safer and better for wildlife than large and deep. Dig a pond roughly 1.5–2 metres across, with a shelf of about 10cm around much of the edge, a second shelf at 20–25cm, and a deepest section of no more than 40cm. Most importantly, leave one side as a long, gentle slope — around one in four — like a natural beach. Steep, slippery liners drown amphibians, hedgehogs and birds; a gradual edge lets everything walk in and out, and gives frogs a place to bask.

Line the hole with butyl or EPDM, laid over a protective underlay. On sandy or stony coastal ground, add a layer of sand or old carpet first. Leave the excavated subsoil as a low bank behind the pond, and set a few flat stones and a log or two along it as basking spots. Fill the pond with rainwater from a butt. Tap water carries nutrients that feed algae, so it is worth waiting for a decent downpour.

Plant it with tough native species

Plants shelter the water, add oxygen and give larvae somewhere to hide. Aim to cover roughly a third of the surface. In an exposed garden, choose low-growing natives that shrug off wind:

• Marginals: brooklime, water forget-me-not, lesser spearwort, marsh marigold and water mint — grown in baskets so they do not take over
• Oxygenators: hornwort and water starwort, which float freely in the water column
• Floating: frogbit, or a single small water lily if your deepest section reaches 40cm
• Damp bank: ragged robin, selfheal and wild angelica, planted into the soil you dug out

Skip yellow flag iris in a small pond — it is far too vigorous and will swamp everything else. Never plant or accept New Zealand pygmyweed, floating pennywort, water fern or parrot's feather; these are banned invasive species in the UK and can spread from a single fragment. And please do not add fish. They eat tadpoles, larvae and almost everything else you were hoping to attract.

What arrives, and when

The speed of colonisation surprises everyone. Within days of filling, pond skaters, water beetles and backswimmers appear, as if from nowhere — they fly, and they find new water fast. Within two or three weeks in summer, damselflies arrive to lay eggs among the stems, with dragonflies following. Frogs usually turn up in the first spring, often announced by a clump of spawn in the shallows, though a garden isolated from other ponds may wait a season or two. Newts take longer but are worth the wait. Be patient, keep the water still, and resist the urge to tidy.

Looking after it through the year

Top up with rainwater in dry spells — coastal wind increases evaporation noticeably — and never let the pond dry out completely. Net out fallen leaves in autumn before they sink and rot, but leave the pond alone through winter, as frogs and newts overwinter in the silt at the bottom. Every few years, cut back vigorous plants in late summer, doing it in patches rather than all at once, and leave the cuttings on the bank for a day so anything caught up can crawl back to the water. If a storm throws salt spray over the pond, do not panic; rain and a rainwater top-up will flush it through. Then simply sit back with a cup of tea and watch the surface come alive.