Why Make Room for Water?

A mini wetland is one of the most generous things you can offer wildlife in a small urban garden. A pond of barely a square metre can draw in damselflies, water beetles, frogs and toads, and the birds and hedgehogs that come to drink. Add British native plants and you create a pocket of genuine habitat — not just a pretty feature, but a functioning little ecosystem humming away between the wheelie bin and the back wall.

The good news is that you don't need to dig up a lawn or own a spade worth the name. A courtyard, a balcony, a concrete yard behind a terraced house: all of them can host water. What follows is the practical version, learned from too many years of trial, error and one memorable explosion of blanket weed.

Choosing Your Container

Almost anything watertight will do: a glazed pot, a half barrel, an old butler sink, a galvanised trough, a lined wooden crate or a sturdy plastic tub. Aim for at least 45cm across and 30cm deep, and go deeper if you can. Forty-five to sixty centimetres of water gives a more stable temperature, a refuge for overwintering creatures, and far less trouble with algae. Avoid narrow-necked containers — wildlife needs a wide landing zone.

Site it where it gets five or six hours of sun for flowering, with a little midday shade if possible. Keep it away from overhanging trees and dripping gutters, since fallen leaves and roots are the two great enemies of a small pond. Finally, make sure the ground is level and firm: a full half barrel is genuinely heavy, and you will not want to move it twice.

Pond, Bog Trough or Waterlogged Planter?

You have three sensible options, depending on space and ambition.

• Mini pond: open water 30–60cm deep, with gently sloping sides or a ramp. Best all-rounder for wildlife.
• Bog trough: a lined container sealed except for a small overflow hole, filled with saturated compost and no open water. Perfect for moisture-loving flowers, and safe where small children are about.
• Waterlogged planter: the simplest of all. No drainage holes, aquatic compost kept permanently wet, planted with marginals and bog plants.

Native Plants That Earn Their Place

Underwater, add two or three bunches of native oxygenators such as hornwort, water violet or water starwort. They keep the water clear and give larvae somewhere to hide. Floating frogbit is charming in a closed container, though never release it into the wild.

Around the margins — the plants that make the whole thing sing — try marsh marigold for its early gold in March, water forget-me-not, brooklime, water mint, lesser spearwort and flowering rush. Yellow flag iris is magnificent but thuggish in a small pot; keep it in its own basket or leave it out. For the boggy zone, ragged robin, lady's smock, water avens, devil's-bit scabious, meadowsweet and grasses such as tufted hair grass and purple moor grass all thrive in permanently damp ground.

Planting Up Without Tears

Use a proper soil-based aquatic compost. Multipurpose compost is far too rich and will feed algae all summer. Plant in baskets or straight into the container, then top with two or three centimetres of washed gravel to stop the compost floating and to deter cats and herons.

Check the depth each marginal prefers: most like their pot rim between just below the surface and 10cm down. Stand baskets on bricks or upturned pots to fine-tune the height, then hide the props with pebbles. Don't overplant — leave at least half the water surface open, both for light and for the creatures that will come to drink.

Access, Water and Seasonal Care

Give wildlife a way out. A log, a gently sloping pile of stones or a strip of pebbles running from water to dry land means frogs, newts and hedgehogs can climb clear instead of drowning. Please don't add fish; they will eat everything worth having.

Top up with rainwater from a butt rather than tap water, which adds the nutrients that fuel algae. Expect a green flush in the first spring — it fades as the plants grow and shade the water. In autumn, clear fallen leaves, but leave seed heads and hollow stems standing until late spring for overwintering insects. During hard frost, float a ball to keep a breathing hole open. That really is all there is to it: a tub of water, a handful of natives, and by June you will have damselflies.