Why a pond earns its place on a smallholding

Of all the habitat you can add to a few acres, a pond gives the quickest return. Dig one this winter and by the following spring you can reasonably expect common frogs spawning in the shallows, smooth newts hunting among the weed, and damselflies drying their wings on the iris leaves by June. Even a modest pond of three metres by two will be found by water beetles, pond skaters and boatmen within a single season, and all that insect life feeds the nestlings in your hedgerow and the bats hunting over the orchard at dusk. Frogs and toads, in turn, take slugs, beetles and leatherjackets out of your beds and away from young fruit trees. It is a lot of wildlife for a weekend's digging.

Orchards and meadows are already rich in invertebrates and rough grass, which is exactly what a new pond needs nearby. The water provides the breeding site; the long grass, tussocks and hedgerow provide the summer hunting ground and the place to overwinter. Put the two together and you have a functioning habitat rather than a decorative puddle.

Siting it properly

Pick a spot that gets sun for at least half the day. Warm water means more insect life and faster tadpole growth, so a south or west-facing bank is ideal, with some shade from the hottest afternoon sun if you can manage it. Keep the pond out of the lowest corner of the field, where rainwater carries in nutrients from the muck heap, the fertilised orchard rows or the track, because nutrient-rich water grows blanketweed and green soup rather than the clear, plant-filled water you want.

Think about roots and services before you dig. Fruit tree roots are mostly modest, but willows, poplars and conifers are not, and any root that reaches a liner will eventually find a way through. Stay clear of field drains, water pipes and cables, and check whether your local authority expects permission for a pond of the size you have in mind. Leave a metre or two of rough, uncut grass around the edge as a buffer and a refuge.

• Minimum size: about 3m x 2m. Anything smaller tends to dry out in a hot summer.
• Central depth: 70–80cm, deep enough to stay frost-free at the bottom so frogs and newts can overwinter in the silt.
• Edge: at least one gently sloping beach, no steeper than 1 in 4, so hedgehogs, birds and amphibians can walk in and out.

Digging the profile

Mark out the shape with a hose or a line of pegs — a wavy, irregular outline looks far more natural than a circle. Strip the turf first and stack it upside down nearby; it will rot down into excellent material for the shelves. Then work in stages, cutting a shallow shelf around the whole perimeter about 20–25cm below the finished water level, a second shelf at 40–50cm for deeper marginals, and finally the central trench to 70–80cm.

If your soil is heavy clay you may be able to puddle it and hold water without a liner, but it is a skill, and a butyl liner with a generous underlay of old carpet or geotextile is far more reliable and will last twenty-five years or more. Line the hole loosely, let it settle, and only then trim and tuck the edges under a turf lip. Fill from water butts if you can; mains water is fine but contains nutrients and chlorine, so let it stand a week or so before planting and expect colonisation to be a little slower.

Planting the shelves

Use native species and plant in baskets of loam or straight into the shelf soil — never a rich compost, which simply feeds algae. On the shallow shelf try marsh marigold, water forget-me-not, brooklime, ragged robin, water mint and lesser spearwort. Yellow flag iris suits the deeper shelf, though it spreads, so keep it in a basket. For oxygenators, hornwort and curled pondweed are reliable and unfussy; common water crowfoot is lovely in moving water but sulks in still ponds.

Leave the water to clear, then add plants gradually over the first summer rather than all at once. Avoid the thugs — Canadian waterweed, parrot's feather and floating pennywort are all but impossible to remove once established, and water lilies should be limited to larger ponds.

The habitat around the water

The pond is only half the story. Part-bury a few logs in a sunny spot nearby — oak, ash and beech are excellent — and leave them to rot. Dead wood supports stag beetle larvae, solitary bees and a host of fungi, and a stone or tile pile beside it will be used by slow worms and, if you are lucky, grass snakes. Leave a patch of nettles and seedheads standing over winter, and resist the urge to tidy the margins.

Looking after it through the year

Never introduce fish; they will eat every tadpole and newt larva in the pond. Never move spawn or plants from another pond either, as amphibian disease and invasive weeds travel that way. Rake leaves out in autumn and leave them on the bank for a day so creatures can crawl back. Pull blanketweed by hand in summer and compost it away from the pond. Keep sprays, fertiliser and muck well out of the catchment, fence livestock off the banks, and top up in dry spells with rainwater only. Then do very little — and watch.