Small ponds punch above their weight

You do not need a sprawling expanse of water to make a genuine difference. A half barrel, an old ceramic sink or a lined hole barely a metre across will pull in frogs, newts, damselflies, water beetles, hoverflies and a surprising range of other creatures within a season or two. In many ways, small garden ponds are better wildlife habitat than large ones: they warm up quickly in spring, which brings amphibians and insects in early, and they are usually free of fish, which is the single biggest favour you can do for tadpoles and larvae.

They are also a pleasure to sit beside. Birds will bathe at the shallow end, hedgehogs will come to drink at dusk, and frogs will take up residence under the dampest stone you can offer them. Because Britain has lost so many countryside ponds over the past century, even a modest barrel in a suburban garden is a real contribution, not a token gesture.

Choosing the right spot and container

Siting matters more than size. Aim for somewhere that receives four to six hours of sun a day, with a little shade in the afternoon so the water does not overheat and turn green. Avoid the drip line of trees and shrubs: fallen leaves feed algae, and roots can puncture liners. The ground must be level — check with a spirit level before you fill anything, because a barrel that is even slightly out will look lopsided forever.

Good containers include a half barrel, a glazed sink, a galvanised trough, or a hole dug out and lined with butyl rubber. A half barrel of around 60–70cm across holds enough water to be stable and is easy to plant. If you are reusing a barrel, make sure it never held oil, weedkiller or wood preservative; if in doubt, line it. An old sink has the advantage of being deep and heavy enough not to blow over, and the plug hole can be sealed with silicone.

Building in a gentle slope

This is the detail most people miss, and it makes the difference between a pond that wildlife uses and one they drown in. Every creature that enters the water needs a way out. Frogs and newts can climb, but hedgehogs, fledglings, bees and beetles cannot.

• Create a shallow beach or shelf at one end, just 2–5cm deep, so birds can bathe and small mammals can drink and climb out.
• Place two or three smooth stones as a stepped ramp from the shelf down into the deeper water.
• Aim for a central depth of 40–60cm. That is enough for frogs to overwinter in the mud without the pond freezing solid.
• If you are lining a hole, build in planting ledges at roughly 10cm and 25cm depth so baskets can sit at the right level.
• Add a piece of roughened wood or a slope of gravel at one corner as an escape route for anything that falls in.

Please don't add fish

Goldfish, and even small native fish, will clear a pond of frogspawn, tadpoles and nearly every insect larva they can find. Leave them out and the pond will stock itself. Insects arrive on the wing within weeks, often before the water has even cleared, and amphibians find new ponds with remarkable speed.

Top up with rainwater from a butt wherever you can. Tap water carries nutrients that encourage algae, and the traces of chlorine and chloramine do the smaller pondlife no favours. A pond filled in autumn or winter, then left alone, usually settles beautifully by spring.

Planting it up

Plant in aquatic baskets filled with heavy garden loam — never potting compost, which floats away and feeds algae. Add a layer of gravel on top to stop the soil washing out and to deter blackbirds from rummaging.

• Marginals: marsh marigold, water forget-me-not, brooklime, water mint, lesser spearwort and ragged robin.
• Oxygenators: hornwort and water starwort, which float freely and help keep the water clear.
• Deep water: a small water lily, if the container is wide enough.
• Avoid: Canadian pondweed, floating pennywort, parrot's feather and water hyacinth. These are invasive and can escape into the wild.

Aim to cover no more than half the surface with floating leaves, so light and oxygen can still reach the water.

Looking after it through the year

Little maintenance is needed, and that is part of the charm. In spring, thin out over-vigorous plants and scoop out surplus blanketweed by twirling it around a cane — a little is normal and healthy. In autumn, net out fallen leaves to keep nutrients down, but leave some leaf litter at the bottom for overwintering creatures.

Never empty and scrub a pond; the sludge at the bottom is a living community, not dirt. In a hard frost, if ice covers the surface for more than a few days, rest a pan of hot water on it to melt a hole so gases can escape. Never smash the ice — the shock can kill amphibians resting below. Then all you need to do is keep the birdbath topped up, put your feet up, and watch what turns up.