A pond is the single most effective thing you can add to a British garden for wildlife. Even a washing-up bowl sunk into a border will draw in creatures that would otherwise pass your plot by. Frogs, newts, dragonflies, damselflies, hoverflies and bats all rely on water, and the smaller the garden, the more valuable every drop becomes. In a terrace with a six-foot patio, a pond the size of a dining table can become the busiest square metre in the whole postcode.
The good news is that small ponds are easier to look after than large ones. They warm up quickly in spring, which means frogspawn develops fast and tadpoles get ahead of predators. They are cheap to dig, quick to plant and, once balanced, need very little from you beyond the occasional tidy.
Position matters more than size. Aim for a spot that gets sun for at least half the day, because warmth drives plant growth and insect activity, but avoid the full glare of a south-facing wall where water can overheat and blanketweed runs riot. Dappled shade from a deciduous tree is ideal, though you should avoid sitting a pond directly under a deciduous tree if you can — fallen leaves will rot and foul the water every autumn.
Mark out a shape with a length of hose or a trickle of sand. Curves look natural; straight edges do not. Aim for a pond roughly 1.2m across and 45–60cm deep at the centre. That depth gives frogs somewhere to overwinter and stops the pond freezing solid in a hard frost, while the shallow shelf around the edge is where birds will bathe and hedgehogs will drink.
Dig the hole with a shelf about 20cm wide and 20cm deep running around the perimeter, then a deeper sump in the middle. Remove every stone and root — a single sharp flint will puncture your liner within a season. Line the hole with a 2–3cm layer of soft sand or old carpet underlay, then lay a butyl or EPDM liner. These are worth the extra cost over cheap polythene, which goes brittle after a couple of winters. Leave plenty of overhang, fill with tap water and let it settle for a week before trimming the edges. Tuck the excess liner under turf or bury it beneath paving so it is hidden.
Do not add fish. They eat everything that makes a wildlife pond interesting, from tadpoles to damselfly larvae, and they turn clear water green.
Plants do the work of a filter, a shelter and a larder all at once. Aim for a third of the surface covered by floating leaves, which shades the water and keeps algae in check. Native species are always the better choice; they support far more insects than ornamental varieties.
Plant in aquatic baskets filled with ordinary garden soil topped with gravel — not potting compost, which leaks nutrients and feeds algae. Lower them gently onto the shelves so the rim sits just below the waterline.
Expect the water to go green in the first few weeks. This is normal and usually clears on its own once plants establish and the microscopic life balances out. Resist the urge to empty and refill; you will only start the cycle again. Do not introduce frogspawn from elsewhere either, as it spreads disease — frogs will find your pond on their own, often within a single spring.
Top up in dry spells with rainwater from a butt rather than tap water, which is rich in nutrients. In autumn, net out fallen leaves before they sink. In late winter, cut back dead stems but leave them in a bundle beside the pond for a few days so any hibernating creatures can crawl back to the water. That is the whole maintenance list — perhaps two hours a year.
Within twelve months you should have frogs, at least three species of dragonfly or damselfly, and a resident blackbird using the shallows as a bath. In a small garden that is a remarkable return on a weekend's digging.
Sedge Notes shares practical, down-to-earth guidance on british wetland gardening and wildlife for readers across the UK.
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