Creating a Wildlife Pond in a Small Garden

Why a Pond Earns Its Place in a Small Garden

A pond is the most generous thing you can add to a small plot. It needn't be large: a hole 1.5m by 1m, with a deeper section at one end, will bring in frogs — and once you have frogs you have froglets in July and a good deal fewer slugs. Add the birds that come to bathe, the water beetles, and the dragonflies that patrol on a summer evening, and a modest hole in the ground starts to feel like a small nature reserve.

Shape matters more than size. A shallow pond with gently sloping sides supports far more life than a steep-sided tub of the same volume. If space is genuinely tight, a half barrel or an old sink will still pull in damselflies and give a hedgehog somewhere to drink.

Siting and Sizing

Choose a spot that gets sun for at least half the day. Frogs spawn in the warmest, shallowest water, and dragonfly larvae need warmth to develop. A pond in full shade will be cold and lifeless, and it will collect leaf litter.

Avoid sitting it under deciduous trees. Falling leaves are the main enemy of a small pond — they rot down into nutrients that feed blanketweed. Keep it away from the house and from anything you might want to sit on, and think hard about small children before you dig. Under-fives and open water are a poor combination. If that is your household, either wait a few years or build a raised pond with a sturdy grid over the open water. It is a real consideration, not a reason to give up.

Digging: Shallow, Sloped, and Simple

Mark out a curved, irregular shape — more edge for the space, and it looks natural. Then dig in layers:

• A shallow shelf of 20–25cm around at least one side, for marginal plants and for birds to bathe in.
• A gentle beach or ramp at one end, sloping from ground level down into the water. This is essential. It lets hedgehogs, frogs and anything else that falls in climb back out. Steep-sided ponds drown wildlife.
• A central area 60–75cm deep. That is enough for frogs to overwinter in the silt and for the pond not to freeze solid. Deeper is unnecessary in a small garden.

Line it with butyl or EPDM rubber — the thicker, the longer it lasts. Put down old carpet, sharp sand or purpose-made fleece underneath to protect the liner from stones and roots. Work it into the shelves, tuck the edges into a shallow trench around the rim, and backfill with soil and turf so no liner shows.

Don't put soil in the bottom. Leave it bare or add a thin layer of sand, plus a few stones or a piece of log in the deep section for creatures to hide under.

Fill it with rainwater from a water butt if you can. Tap water will do at a pinch, but it carries nutrients and phosphates that feed algae, so treat it as a last resort.

Planting with Native Species

Plant in hessian or aquatic baskets filled with garden soil or loam, topped with gravel so the soil doesn't cloud the water. Never use multi-purpose compost — it is far too rich and will feed algae all summer.

• Marginals for the shallow shelf: marsh marigold, water forget-me-not, water mint, lesser spearwort and flowering rush. Yellow flag iris is lovely but vigorous — keep it in a basket and divide it regularly.
• Oxygenators such as hornwort and curled pondweed. These float in the water rather than sitting in baskets and are the workhorses of a healthy pond.
• Floating plants: a single small water lily, or frogbit for a tiny pond. Avoid duckweed, and avoid floating pennywort, parrot's feather and water fern entirely — they are invasive and illegal to let spread into the wild.

Leave the edges rough. Long grass, a log pile and a few stones around the rim give amphibians somewhere to hide when they leave the water, and give insects somewhere to overwinter.

Leave the Fish Out

No fish. This is the single most important rule, and the one most often broken. Fish eat frogspawn, tadpoles, newt larvae and dragonfly nymphs. A goldfish pond, however pretty, is a wildlife desert by comparison.

Equally, don't introduce frogspawn from someone else's pond. You risk bringing in ranavirus and other diseases, and you do the donor pond no favours. Frogs find new ponds remarkably quickly on their own. Newts take longer — sometimes two or three years — but they will come.

Letting It Fill and Letting It Be

Newly filled, your pond will almost certainly turn green within a fortnight. This is normal. Don't drain it and start again; it is a phase, and the plants and microscopic life will clear it within a few weeks as they establish.

After that, your jobs are small:

• Scoop out fallen leaves in autumn before they sink.
• Twist blanketweed out by hand in spring with a stick, like candyfloss. Never use chemicals.
• Top up in dry spells with rainwater, not tap water.
• Cut plants back in autumn and leave the cuttings on the bank for a day so anything clinging on can crawl back.
• Never empty and scrub the pond. That is the classic mistake — you would throw away the entire community living in the silt. A wildlife pond is never "cleaned".

Within a year you will have frogs, water beetles, pond skaters and damselflies. Give it two or three and the dragonflies arrive — southern hawkers and common darters are usually the first, and they will hunt over the garden for the rest of the summer. For the price of a weekend's digging, that is a remarkable return.