Why a Pond Earns Its Place in a Small Garden

Of all the things you can add to a modest British back garden, a wildlife pond gives the biggest return for the least space. A sunken basin barely a metre and a half across, planted with native oxygenators and given one gently sloping edge, will pull in frogs, smooth newts, damselflies and the occasional dragonfly within a single season. It does not need a pump, a filter, a fountain or a single goldfish. In fact, it works far better without them.

Garden ponds have become genuinely important for UK wildlife. Since the middle of the last century we have lost vast numbers of countryside ponds, and the humble garden has quietly taken up the slack. Your half-barrel-sized puddle in Leicestershire or Cardiff is not a novelty — it is habitat.

Siting It: Sunlight, Shade and Rainwater

Aim for four to six hours of sun a day. Dragonflies and damselflies need warmth to hunt, and most aquatic plants flower best in decent light. A little afternoon shade is welcome, though, as it keeps the water cooler and slows the algae that plague new ponds.

Avoid sitting it directly beneath a deciduous tree — you will spend every October fishing out leaves — and steer clear of anywhere that runoff from a patio or a well-fed flower border drains in. Nutrients are the enemy of clear water. Rainwater is far better than the tap: mains water carries chlorine and, more importantly, phosphates and nitrates that feed algae. Fill from a water butt if you can, or simply dig the hole in autumn and let the rain do the work.

Digging the Basin: Depth, Shelves and Slopes

Autumn is the ideal time to dig. The pond then has all winter to settle, and frogs will find it before they spawn in February and March.

• Centre depth: 60–75cm is the classic figure, deep enough to stay cool in summer and to give frogs somewhere to overwinter. In a very small garden, 45–60cm is perfectly adequate.
• A planting shelf: 20–25cm deep and 25–30cm wide along at least one side, for marginal plants.
• A gentle slope: one end graduating from dry ground down to about 10cm, so amphibians, hedgehogs and thirsty birds can walk in and out without drowning.

Line the hole with underlay and then butyl or a good flexible liner, and tuck the edge into a shallow lip so that the finishing stones hide it. Gravel over the shallow end makes a natural-looking beach and gives you somewhere to stand a plant pot.

Planting with Native Oxygenators and Marginals

Plant heavily from the start — bare water simply grows algae. Oxygenators are the engine room of the pond, competing with algae for nutrients and giving newt tadpoles and dragonfly nymphs somewhere to hide.

• Hornwort (Ceratophyllum demersum)
• Spiked water-milfoil (Myriophyllum spicatum)
• Water starwort (Callitriche species)

Around the edges, marsh marigold gives you early gold in April, followed by water forget-me-not, brooklime, water mint and lesser spearwort. Add a little frogbit on the surface for cover, but not so much that it shades everything out.

Do avoid the thugs. Floating pennywort, parrot's feather, water fern and New Zealand pygmyweed are all invasive non-natives, and it is an offence to allow them to spread into the wild. Buy from a reputable supplier and never tip a pond plant into a river or canal.

Stones, Logs and Escape Routes

A pond without exits is a trap. Stack a few flat stones at the shallow end to form a ramp, and lay a piece of rotting log half in and half out of the water. Dragonfly nymphs climb stems and stones when they emerge as adults, and a log gives them the perfect ladder. A sloping plank or a stone at the edge does the same job for a hedgehog that has wandered in for a drink.

Leave one corner of the garden wild: a small pile of logs, some leaf litter and a patch of long grass. Frogs spend most of the year out of the water, and they need somewhere damp and untidy to sit.

What Will Arrive, and How to Keep It Thriving

Frogs usually appear within weeks, and you may find spawn the first spring. Smooth newts and palmate newts arrive quietly, often at night. Damselflies — large red and azure are the usual first comers — will be hunting over the water by midsummer, with common darters and hawkers following as the pond matures. Pond skaters, water boatmen and diving beetles turn up on the wing, seemingly from nowhere.

One important rule: never move spawn, tadpoles or newts between ponds. Great crested newts are fully protected by law and must not be handled or relocated, and moving amphibians spreads disease. Let your pond fill itself.

Maintenance is light. Net out excess duckweed rather than chasing every last leaf, thin blanketweed in late spring, and clear fallen leaves in autumn — but leave a few for the invertebrates. Never use chemicals near the pond, and never add fish, which will eat everything that makes the pond interesting. A short winter freeze is harmless in a deep enough basin.

Give it a season. By next June you will have froglets in the long grass, damselflies on the mint flowers and a garden that hums in a way it never quite did before.