A pond earns its place in a coastal garden

Gardens by the sea sit on a busy flight path. Estuaries, cliff tops, headlands and dune edges all funnel birds along the coast, and those birds are often short of one thing: fresh water. A rock pool is salt. A stream may be a mile away. So a modest garden pond, even one no bigger than a dining table, becomes a genuine pit stop for drinking, bathing and preening.

Gulls, oystercatchers and turnstones will use a coastal pond when they can find one, and the everyday visitors matter just as much — pied wagtails, rock pipits, starlings, sparrows, swallows and house martins. House martins will even collect beakfuls of wet mud from a soft margin for nest building. Build the pond with birds in mind and it will quietly become the busiest patch in the garden.

Shallow edges are the single most important detail

Birds need to walk in and out of water, not plunge in. A steep-sided pond, however pretty, is a hazard rather than a bath. Give one whole side a gently shelving shelf that slopes from dry ground into the water, so a bird can wade in until it is belly-deep.

• Create a shelf 5 to 10cm deep and at least 60cm wide — a metre is better, giving several birds room at once.
• Cover the liner with gravel or small pebbles so feet get grip and the bottom is not slick.
• Add a half-submerged log or a few flat stones as perches for drinking and for preening afterwards.
• Keep the middle 45 to 60cm deep — enough to stay cool and safe in summer, shallow enough to be manageable.
• Sit the pond in the open, with clear sightlines, but tuck it just behind a windbreak hedge or wall so birds are not sitting in salt-laden gales.

Position it away from overhanging shrubs where a cat can lurk, and never directly under a feeder, where dropped seed and droppings foul the water within weeks.

Plant it like a coastal marsh, not a garden centre display

Native plants give cover, shade and insect life, and they suit a windy, salty site far better than tender ornamentals. Aim to leave roughly half the surface open so birds have a clear landing and take-off zone.

• Marginals: marsh marigold, brooklime, water mint, water forget-me-not, lesser spearwort and water plantain.
• Structure: soft rush, jointed rush and greater pond sedge for upright cover at the edge.
• Oxygenators: hornwort, water starwort and curled pondweed, submerged in the deeper water.
• Dry banks and spoil: sea thrift, sea campion and lady's bedstraw, which shrug off wind and spray.

Avoid floating pennywort and water fern entirely — both are invasive and should never be planted or moved between sites. It is also worth resisting flag iris if your pond is small, as it spreads fast and will soon squeeze out the open water birds need.

Leave the fish out

This is the advice most coastal gardeners find hardest to accept, and the one that matters most. Goldfish and koi graze through invertebrate larvae and tadpoles, stir up sediment and add nutrients, turning clear water green. A pond of a few square metres can be stripped of its insect life by a handful of fish.

There is a second reason. Fish attract predators. In a coastal garden you are not only inviting herons; you are inviting gulls, and in some places cormorants and otters, all of which will clear a small pond and then keep returning to check it. A fishless pond is a quieter pond, and a far richer one. If your pond already holds fish, simply do not add more, and let the population settle.

Coastal quirks: salt, spray and top-ups

Wind-blown salt will stress pond plants, so avoid siting the pond where storm spray lands directly and where any seawater could wash in. Shelter from a hedge or wall helps, provided the flight line in stays open.

Top up with rainwater from a butt wherever possible. Tap water carries nutrients and encourages blanketweed; an occasional splash in a dry spell is fine, but regular tap top-ups are the fastest route to pea-green water. Similarly, keep fertiliser, weedkiller and driveway run-off away from the pond, and never use chemical treatments in the water itself.

Small practicalities save lives. Leave a gently sloping stone or a piece of roughened timber at the margin so hedgehogs and other ground wildlife can climb out. Skip netting over the water, which tangles birds, and never feed bread — it fouls the water and offers birds very little.

Quiet care through the year

Clear fallen leaves in autumn before they sink and rot, and lift excess blanketweed by hand in spring, leaving some for the insects and tadpoles. Let the margins grow a little wilder than the rest of the garden; that rough edge is where birds shelter between baths.

If ice forms, float a ball or pour warm water over it, rather than breaking it, which harms wildlife beneath. Then do very little else — and give it time. Ponds take a season or two to settle and to be found. The first wagtail bobbing on the pebbles will tell you it has worked.