Why a Small Pond Is Worth the Spadework

If you do only one thing for wildlife on your patch this year, dig a pond. Nothing else comes close for the sheer number of creatures it draws in. Within a season of filling, a modest hole in the ground becomes a nursery, a larder and a bathing station: common frogs, smooth newts, damselflies, dragonflies, hedgehogs drinking at dusk and a constant procession of birds splashing about on a warm afternoon.

It does not need to be grand. Two metres by one and a half is plenty to start with, and a pond that size will keep a small garden buzzing from March to October. Frogs will repay you by hoovering up slugs after dark, and the dragonflies will repay you by simply being there. Best of all, a pond asks very little of you once it has settled — a bit of planting, a top-up in dry spells and a refusal to interfere.

Siting It and Getting the Shape Right

Pick a spot that gets sun for at least half the day. Frogs and dragonflies need warmth, and the plants will sulk in deep shade. Some shade at midday is no bad thing, though, as it keeps the water from overheating and cuts down on algae. Avoid sitting it directly under deciduous trees — you will spend every autumn fishing out leaves — and keep it away from anywhere that collects runoff from a road, a muck heap or heavily fertilised beds.

Put it somewhere you can see from the kitchen window. You will notice far more, and you are far more likely to keep an eye on it.

The shape matters more than the size. Aim for gentle edges rather than steep sides, and work in three distinct zones:

• A shallow beach on at least one side, sloping gradually into the water, so birds, hedgehogs, frogs and newts can walk in and out without drowning. This is the single most important feature of a wildlife pond.
• A planting shelf around 20–25cm deep for marginal plants in baskets.
• A deeper section of 60–75cm across a good third of the pond. This gives frogs somewhere to overwinter in the mud and stops the water boiling in August or freezing solid in February.

Mark the outline with a rope or hosepipe before you start digging and give it an irregular, wiggly shape. A wobbly oval looks natural; a neat circle looks like a sunken paddling pool.

Digging, Lining and Filling

Lift the turf first and stack it upside down in a corner for a few months — that gives you lovely crumbly loam for the planting baskets later. Then dig, removing sharp stones and any roots that could puncture the liner. Line the hole with a soft layer of old carpet, sand or purpose-made underlay fleece before the liner goes in.

Butyl rubber lasts decades but costs more; good-quality flexible liner is a sensible middle ground, while the cheapest PVC goes brittle and will have you digging it out again in a few years. Buy generously — allow the width, plus twice the depth, plus 60cm of overlap. Weigh the edges down with turf or stones and hide them with gravel and plants. Do not trim the liner until the pond is full, as the weight of water will pull it into every corner.

Fill it with rainwater from a butt if you can. Tap water is perfectly workable if that is all you have, but let it stand for a few days before planting.

Planting: Oxygenators, Marginals and a Little Restraint

Go native and go steady. Plant in aquatic baskets using heavy garden loam or soil — never potting compost, which will feed the algae rather than the plants.

• Oxygenators: hornwort, curled pondweed and water starwort. These do the quiet work of keeping the water clear.
• Marginals: marsh marigold, water forget-me-not, water mint, lesser spearwort, purple loosestrife and yellow flag iris.
• Damp-edge plants: ragged robin and meadowsweet for the boggy ground around the rim.

Cover roughly a third of the surface in the first year, and no more than half in later years. Too few plants and you get green soup; too many and the water goes stagnant. Steer well clear of invasive non-natives such as New Zealand pygmyweed, floating pennywort, water fern and parrot's feather, and never lift plants from the wild — it is illegal, and it is how those problems spread.

Leave the Fish Out

It is tempting to add a few goldfish, but please don't. Fish eat frogspawn, tadpoles, newt larvae and dragonfly nymphs. They also need feeding, which loads the water with nutrients and turns it green, and then they need filtering on top. A fish-free pond finds its own balance and needs almost nothing from you. It also means no heron standing on your lawn looking disappointed.

Year-Round Care With Minimal Fuss

Top the pond up in dry spells with rainwater rather than tap water. Always leave a log, a stone or a gently sloping ramp in the water so anything that tumbles in can climb back out — a plank in the corner has saved countless hedgehogs. Thin oxygenators by hand in late summer and leave the excess on the edge overnight so any creatures caught up in it can crawl back.

Skim off the worst of the autumn leaves but leave a few, and resist the urge to tidy the margins until late spring, when overwintering insects have emerged. Above all, keep slug pellets, weedkillers and pesticides well away from the pond and its surrounds — a single dose of runoff can undo a whole year's work. If you have toddlers about, a raised pond or a sturdy removable grid for a couple of years is the sensible compromise. Then sit back, and let the frogs do the rest.