Sophie Bennett
Why a garden pond is the best thing you can add this spring
Few garden projects repay you quite so generously as a wildlife pond. Within weeks of filling one you can expect beetles rowing about in the shallows, damselflies perched on the rushes, and — if you get the design right — common frogs spawning in February and smooth newts wrapping their eggs in the leaves of water plants by May. In a country that has lost huge numbers of ponds over the last century, a modest hole in the ground holding a few hundred litres of rainwater is genuinely useful conservation work.
Spring is a fine time to build one, provided you avoid the hottest, driest spells. The soil is workable, the plants you buy will establish fast, and amphibians are on the move looking for somewhere to breed. Best of all, you do not have to spend much. A spade, a liner, a bucket of native plants and a bit of patience will do it.
Choosing the right spot
Amphibians are cold-blooded, so they seek out warmth. Aim for a pond that receives about four to six hours of sunshine a day, ideally catching the morning sun and dappled shade in the afternoon. Full sun all day encourages blanketweed and green water; deep shade keeps the water cold and the frogs away.
Position it away from mature trees and shrubs. Falling leaves rot down and feed the algae, while thirsty roots can puncture a liner. Keep well clear of anywhere you use weedkiller, fertiliser or slug pellets, since run-off will poison the water. A spot you can see from a kitchen or living room window is a bonus — you will watch it far more than you expect.
- Sun: four to six hours daily, morning sun preferred.
- Clear of trees: no heavy leaf fall, no invading roots.
- Away from chemicals: no run-off from beds or paths.
- Safe edges: if you have toddlers or visiting grandchildren, plan a shallow pebble shelf or a low mesh cover.
Digging it out: slopes, shelves and depth
Amphibians need two things above all: a way to walk in and out, and somewhere deep enough to sit out a frost. Dig a pond at least 60cm (2ft) deep in the middle, and 75cm to a metre if you have the space — that keeps the water cool in summer and stops it freezing solid in winter. Frogs often overwinter in the bottom mud, so depth matters.
Then build in gentle slopes rather than sudden drops. Create one long, shallow ramp at roughly 30 degrees down to the water, and a series of planted shelves at 10cm, 25cm and 45cm below the finished water level. Line the hole with a butyl or flexible liner, underlay it against stones, and use the excavated soil to raise a low bank behind the pond where damp-loving plants and log piles can sit.
Fill with rainwater from a butt wherever possible. Tap water contains nutrients and chlorine; if you must use it, let it stand for a few days first. Leave the pond to settle for a week before planting.
Planting with British natives
Native plants do the heavy lifting. They oxygenate the water, shelter tadpoles and give newts somewhere to lay. Plant in baskets of soil topped with gravel to stop the compost clouding the pond, and include a mix of submerged, floating and marginal species.
- Oxygenators: hornwort and water starwort for clear water.
- Marginals: marsh marigold, lesser spearwort, water forget-me-not, ragged robin and water mint.
- Structure: yellow flag iris and purple loosestrife — handsome, but plant them in baskets to keep them in check.
- Surface cover: a small water lily or frogbit, covering roughly a third of the surface.
Steer clear of invasive non-natives such as floating pennywort, parrot's feather and water fern. Never take plants or spawn from the wild, which spreads disease and damages existing ponds.
Making it easy for frogs and newts to come and go
This is the detail that decides whether your pond succeeds. A frog can haul itself out of a pond with steep sides, but a newt often cannot, and both waste energy scrabbling at a vertical liner. Give them a proper exit.
- A pebble beach: pile smooth stones and gravel on one slope so it forms a shallow ramp into the water.
- A log ramp: lay a weathered branch or two from the bank into the pond, weighted with stones.
- Plant cover right to the edge: dense marginals give amphibians somewhere to hide while they cross open ground.
- Damp corridors: leave a wild patch of long grass, and add a small log pile or rockery nearby for shelter and hibernation.
Do not introduce fish. Even a few goldfish will clear a pond of tadpoles in a season. Let your pond colonise naturally instead — frogs and newts find new water remarkably quickly.
What to expect through the year
Common frogs usually arrive to spawn in February or March, leaving clumps of jelly in the shallows. Smooth and palmate newts follow from March to June, laying single eggs folded into plant leaves — check water forget-me-not and starwort for them. By midsummer the pond will be alive with insects, and by autumn you should leave fallen leaves out of the water where you can.
Keep maintenance gentle: clear excess weed by hand in late summer, leave seed heads and marginals standing over winter, and never empty and scrub the whole pond at once. Top it up with rainwater in dry spells and resist the urge to tidy too much. A slightly shaggy pond is a healthy one — and come next spring, you will hear the frogs before you see them.
