Native Plants Do the Work Exotics Cannot

A well-planted pond is the single most productive wildlife feature most of us can add to a British garden. Frogs, newts, damselflies, diving beetles and a cloud of hoverflies will find a small pond within a season or two, provided the planting suits them. That proviso matters more than most of us realise.

Native pond plants have evolved alongside our invertebrates for thousands of years, and that shared history shows. Damselfly nymphs climb the soft stems of water mint and water forget-me-not before they take to the air. Tadpoles graze the algae that gathers on the submerged leaves of hornwort and water-crowfoot. Hoverflies and bumblebees work the flowers of purple loosestrife and marsh marigold in a way they rarely bother with exotic ornamentals. Choose the familiar native species and you are feeding and housing creatures that already know what to do with them.

The Four Layers of a Native Pond

Think of a pond in layers, from the open water down to the damp ground at the edge. Each layer has its own native specialists, and a good wildlife pond contains all of them.

• Oxygenators — submerged plants such as hornwort, spiked water-milfoil and common water-crowfoot. They keep the water clear, shelter newt larvae and small invertebrates, and give tadpoles and water snails something to graze.
• Floating plants — native frogbit and, in larger ponds, white water-lily. Their leaves provide shade, basking platforms for insects and egg-laying sites for some damselflies.
• Emergent marginals — yellow flag iris, purple loosestrife, water mint, water forget-me-not, lesser spearwort and bog bean. These are the stems damselfly nymphs climb to emerge, and the flowers that feed pollinators right through summer.
• Bog and damp-ground plants — ragged robin, meadowsweet, soft rush and tussock sedge, planted just outside the liner where the soil stays consistently moist. Frogs and toads use this zone as cover when they move to and from the water.

Two or three plants from each layer will fill a small pond comfortably. Resist the temptation to crowd everything in at once; allow a third of the surface to stay open water, and let the plants grow into it.

What the Wildlife Is Actually Using

It helps to know what each group of creatures needs, because it shapes both your planting and your maintenance.

• Tadpoles graze algae and soft plant tissue, so dense oxygenator growth in sunny water is essential, particularly from May to June.
• Damselflies and dragonflies need upright stems for emergence and, for many species, submerged plant tissue or floating leaves for egg-laying. Iris, water mint and frogbit all earn their place here.
• Water beetles, including the great diving beetle, hunt among submerged plants and lay eggs in the stems of marginals and floating vegetation.
• Pollinators — water mint and purple loosestrife flower late and are worked hard by bumblebees, hoverflies and honeybees well into September.
• Frogs, toads and newts need shallow, plant-rich edges to spawn and damp cover nearby for the rest of the year.

Planting Well: The Practical Detail

Plant in late spring or early summer, when the water has warmed and the plants will root quickly. Use aquatic baskets lined with hessian, filled with ordinary garden loam — not potting compost, which is far too rich, and never peat. Top each basket with a layer of gravel to stop the soil escaping and to stop blackbirds flicking the contents into the water.

One plant per basket is usually plenty. Sink marginal baskets so the top sits just below the waterline; oxygenators are simply dropped in as loose bunches weighted with a stone. Aim for roughly one bunch of oxygenators per square metre of open water, and let water lilies cover no more than a third of the surface. Do not add fertiliser of any kind, and do not add fish. Goldfish will clear a wildlife pond of tadpoles and invertebrate life remarkably quickly.

Year-Round Care Without Losing the Tenants

Wildlife ponds are meant to be managed gently, and the timing of your tidying matters more than the tidying itself.

• Thin oxygenators in late summer if they are swamping the pond. Leave the cuttings on the bank for a day so shrimps, snails and insect larvae can crawl back in.
• Leave margins standing over winter. Seed heads feed birds, and hollow stems shelter overwintering insects.
• Avoid a full autumn or spring clean-up. Frogs often overwinter in the silt at the bottom, and tadpoles are present in spring.
• If stems do need cutting, do it in late spring once tadpoles have grown, and take only a portion in any one year.
• Never empty and scrub the pond. The algae and silt you are removing are the base of the food web.

Keeping the Pond Genuinely Native

Some of the worst problems in British ponds have come from plants sold as attractive aquatics. New Zealand pygmyweed, floating pennywort, water fern and parrot's feather are all non-native and all capable of smothering a pond and spreading into the wider countryside. Check labels carefully, buy from suppliers who state British native provenance, and never tip pond contents into a stream or ditch.

If you do nothing else this year, plant hornwort, water mint and yellow flag iris. Between them they cover grazing, egg-laying and emergence for a surprising number of our native pond creatures — and they will make the whole garden feel far more alive.