Creating a Pond for Garden Wildlife

Why water beats almost anything else you can add

Water is the single most effective thing you can put in a British garden for wildlife. Even a modest pond — two or three metres across, with a deepest point of sixty centimetres — will draw in creatures that simply cannot use a border or a hedge. Frogs, toads and smooth newts turn up to breed within a season or two. Dragonflies and damselflies hunt over the surface and lay eggs on submerged stems. Birds come to drink and bathe, and bats swoop low at dusk to take the insects rising off the water. You also get something quietly wonderful to watch from the kitchen window in February, when the first frogs return and start calling.

Siting the pond: light, shelter and access

Position matters more than design. Aim for a spot that receives sun for at least half the day, because warmth drives the insect life everything else depends on. Avoid full sun all afternoon in a small garden, though, as the water can overheat and blanketweed will thrive. Keep well away from large trees: fallen leaves rot down and release the nutrients that feed algae, and roots can puncture a butyl liner.

Think about practicalities too. You will need to top the pond up, thin out plants and occasionally scoop out leaves, so leave a firm, level route to the edge. If young children use the garden, a shallow shelf or a simple fence is far better than abandoning the idea. A pond you feel relaxed about will be enjoyed far more than one you are anxious about.

Size, depth and shape

You do not need a large pond, but depth matters enormously. A pond that freezes solid to the bottom will kill overwintering frogs and newts, and there is nothing you can do about it once the ice forms.

• Depth: at least 60cm at the lowest point, ideally 75cm in a cold, exposed garden.
• Shelves: one or two ledges at 20–30cm for marginal plants and for birds to stand on.
• Edges: slope at least one side gently, or add a roughened plank or a stone ramp. Hedgehogs, frogs and young ducklings drown in ponds with sheer sides.
• Beach: a shallow pebbled area gives birds a safe place to bathe and drink without getting waterlogged.

A flexible butyl liner is the most straightforward option and will last decades. Line the hole with a layer of soft sand or old carpet first, and leave a wide overlap around the edge to tuck under turf or paving.

Planting for cover, oxygen and nectar

Plants do the heavy lifting: they oxygenate the water, shade out algae and give larvae somewhere to hide. Use native species where you can, and plant marginals in baskets filled with ordinary garden soil topped with gravel — not rich potting compost, which leaks nutrients and turns the water green.

• Oxygenators: hornwort or water starwort, submerged in the deepest part.
• Marginals: water forget-me-not, marsh marigold, water mint, yellow flag iris and purple loosestrife around the edges.
• Floating: a native white water lily, which shades the surface without covering it completely.

Green water in the first spring is completely normal. It clears as the plants establish and out-compete the algae. Do not reach for a chemical treatment — a wildlife pond should never see one. Keep slug pellets away from the surrounding beds, as they are lethal to frogs and newts.

Why fish and a wildlife pond do not mix

It is the most common mistake, and an understandable one. Fish eat tadpoles, newt larvae and dragonfly nymphs, and they stir up sediment that clouds the water and feeds algae. Goldfish in particular will strip a pond of invertebrate life within a season. Herons will then take the fish anyway, so you end up with the worst of both worlds.

Pumps and fountains are similarly unnecessary. Moving water is pleasant to listen to, but filters and fountains draw in larvae and can trap them. If you want the sound of water in a wildlife garden, a separate small water feature fed by a solar pump is a better solution.

Looking after the pond through the year

Fill the pond from a water butt wherever possible. Tap water contains nutrients that encourage algae, so keep it as a last resort. Top up in dry spells rather than letting the level drop and expose the liner.

In autumn, scoop out fallen leaves before they sink and rot, but leave a few at the bottom for larvae to shelter in. In winter, do not smash the ice — the shock waves can kill frogs resting in the mud. Instead, stand a pan of hot water on the surface until a hole melts through. In spring, pull out excess weed with a fork and leave it on the edge of the pond overnight, so anything caught up has a chance to crawl back in.