Why a small pond punches above its weight

A pond is the single most effective thing you can add to a garden for wildlife, and it does not need to be grand. Even a modest pool of one and a half metres by a metre will draw in common frogs, smooth newts, dragonflies, damselflies, water beetles, pond skaters and a host of bees and hoverflies that come down to drink. In a tidy garden, it becomes the one place where things are allowed to be messy, damp and full of life.

The key is to stop thinking of it as a water feature and start thinking of it as a habitat. That shift changes every decision: where you put it, how you shape it, what you plant and — crucially — what you refuse to put in it.

Choosing the spot and getting the shape right

Pick a position that gets sun for at least five or six hours a day. Warm water speeds up tadpole development, which matters enormously in a British summer that can turn cool and wet without warning. Some late afternoon shade is fine, and it helps keep algae in check.

Avoid the drip line of big trees and shrubs. Falling leaves will rot down and feed the algae, and roots can eventually pierce a liner. Also steer clear of any spot that collects runoff from a patio, drive or treated lawn, because you do not want fertiliser or weedkiller washing in.

For the shape and depth, aim for:

• A shallow shelf about 15–20 cm deep around part of the edge, for marginal plants and for frogs to sit in.
• A gently sloping beach at one end — a ramp of stones, gravel or turf — so amphibians, hedgehogs and insects can climb in and out. Vertical sides are a death trap.
• A deeper section of 45–60 cm in the middle, which gives frogs and newts somewhere to overwinter and keeps the pond from drying out completely in a hot August.
• An undulating edge rather than a neat circle. Curves and bays create sheltered pockets and look far more natural.

If small children use the garden, a raised pond with a sturdy grid just below the surface, or a shallow pebble beach that leaves no deep water, is the sensible compromise.

Lining, filling and the water you use

Butyl rubber is the most forgiving liner for a dug pond — it is flexible, long-lasting and easy to mould around shelves. A preformed rigid liner is quicker but more restrictive in shape. Whichever you choose, line the hole with old carpet, sand or underlay first, and leave a generous overlap around the edge before tucking it under turf or paving.

Fill the pond with rainwater. A water butt plumbed to a downpipe is ideal, and it is worth waiting for a wet spell rather than reaching for the hose. Tap water contains chlorine and, more importantly, nutrients that will fuel a bloom of blanketweed and green water. If you genuinely have no alternative, fill slowly and let the pond settle for a fortnight before planting.

Let the water stand for a few days so it reaches ambient temperature, then start planting. Never use tap water to top up in summer if you can avoid it — a spare water butt kept specifically for the pond is one of the best investments you can make.

Planting for a British pond

Use native species, plant them in aquatic baskets filled with heavy loam rather than rich compost, and top the baskets with gravel to stop fish — or blackbirds — flinging the contents about. Aim for a mix of three groups:

• Marginals for the shelf and edges: marsh marigold, water forget-me-not, brooklime, lesser spearwort and ragged robin.
• Oxygenators for the deeper water: hornwort and water starwort, which shelter tadpoles and give newts somewhere to lay eggs.
• Floating plants for shade and cover: frogbit or a little native water lily in a larger pond.

Cover no more than half the surface, so light and oxygen can still reach the water. And be strict about what you refuse: floating pennywort, parrot's feather and New Zealand pygmyweed are invasive, illegal to sell, and will smother a small pond within a season. Water soldier is banned from sale in England and Wales for the same reason.

Why fish are the one thing to leave out

Fish and wildlife ponds simply do not mix. Even a few goldfish will hoover up frogspawn, tadpoles and every insect larva they can find, and they stir up sediment while adding nutrients that feed algae. A pond without fish is a pond where invertebrates can build up real numbers — and that is what brings in the dragonflies.

Letting wildlife arrive, and looking after it

The most common mistake is trying to stock the pond. Frogs, newts and dragonflies will find it on their own, often within a season, and moving spawn, plants or water from another pond risks spreading disease, invasive species and — in the case of great crested newts — breaking the law.

Once it is up and running, keep interference gentle:

• Twist out blanketweed by hand rather than treating it with chemicals, and leave it on the edge for a day so anything caught in it can crawl back.
• Top up with rainwater in dry spells; a pond that dries out will kill developing tadpoles.
• Leave dead stems and fallen leaves in place over winter, and build a small log or stone pile nearby as a hibernation spot for frogs and newts.
• Cut back vigorous growth in autumn if it is taking over, but always leave some cover.

Do this, and within a couple of years you will have a pond that hums, croaks and glitters with dragonflies — a small patch of British countryside sitting at the bottom of your garden.