Why a small pond punches above its weight

A pond is the single most valuable thing you can add to a small garden. Even one buried in a container barely a metre across will be found within weeks by frogs, smooth newts, damselflies, pond skaters and diving beetles. Garden ponds have become genuinely important for UK wildlife, because so many natural ponds have vanished from the wider countryside. Size matters far less than depth, water quality and a gentle way in and out. Get those right and a pool the size of a washing-up bowl can hum with life by midsummer. It also gives your garden birds somewhere to drink and bathe, which is a gift in a hot spell.

Choosing the spot and the container

Pick a spot that gets sun for part of the day. Three to five hours is ideal: enough warmth for dragonfly larvae to develop, but not so much that the water turns into green soup by July. Avoid ground beneath a tree or overhanging shrubs, because fallen leaves rot down and feed algae, and avoid deep shade entirely. A spot you can see from a window is a bonus, because you will actually watch what turns up.

For a small garden, a preformed rigid liner is the simplest option — a 90cm by 60cm shape with built-in planting shelves is perfect. A buried plastic tub, a Belfast sink or a sturdy trug will also do, provided it has never held anything chemical. Whatever you use, aim for a maximum depth of at least 45cm, so frogs can overwinter in the mud below the ice. If you have very young children, a raised container or a rigid mesh cover fitted over the top is a sensible precaution.

Digging in and getting the levels right

Mark out the shape, then dig the hole a few centimetres wider and deeper than the container. Sit it in, check the rim is level with a spirit level, and pack sand or old carpet underneath to cushion it. Backfill around the sides with the soil you removed, firming it as you go.

Leave the rim about 2cm proud of the surrounding soil. That tiny lip stops soil washing in and stops garden chemicals draining in, but it also creates a barrier for small creatures, so you must add a ramp. Fill the pond with rainwater from a water butt rather than tap water, which is full of nutrients and chlorine and will trigger an algae bloom. Then leave it for a week or two to settle before planting.

Planting with natives — and what to avoid

In a small pond, restraint is everything. Four or five species will look generous without swamping the water. Plant in aquatic baskets filled with loam-based soil or ordinary garden soil, topped with a layer of gravel to stop it clouding the water.

• Marginals: marsh marigold, water forget-me-not, lesser spearwort and water mint give cover, colour and perches for emerging dragonflies. Stand them on the shelves so their crowns sit just below the surface.
• Oxygenators: hornwort and water starwort stay submerged and help keep the water clear, giving newts and insects somewhere to hide.
• Floating: a little frogbit or water crowfoot provides shade that discourages blanketweed.

Never plant invasive non-natives such as New Zealand pigmyweed, water fern or parrot's feather. They are illegal to plant in the wild and will destroy a small pond within a season. And please resist adding fish: they eat tadpoles and larvae, and turn clear water muddy.

Ramps, beaches and bird-friendly edges

An escape route is the difference between a pond that supports wildlife and a trap. Hedgehogs, frogs, fledgling blackbirds and thirsty bees all fall in, and a steep-sided container has no way out. Add at least one gently sloping plank, flat stone or folded strip of pond liner that runs from the water to dry ground, and keep it in place all year. A bundle of stones stacked into a shallow staircase works just as well.

Add a pebble beach too — a shallow area of rounded stones and gravel at one edge, sitting barely below the waterline. Birds will use it for drinking and bathing, and insects will bask there. A few larger stones around the rim give dragonflies somewhere to rest and warm up in the morning sun.

Looking after it through the year

Maintenance is light if you get the basics right. In autumn, net out fallen leaves before they sink — usually the single biggest cause of a green, smelly pond. In spring, twirl a stick through excess duckweed or blanketweed and leave what you remove on the side of the pond for a day, so any trapped creatures can crawl back in.

Top up with rainwater in dry spells, and never empty and scrub the pond — that destroys the whole community of microscopic life it depends on. If you are lucky enough to get frogspawn, leave it where it is, and do not move spawn between ponds, as this spreads disease.

Within a season or two you should have frogs, at least one species of newt and a parade of damselflies. That is a serious amount of wildlife for a corner of a town garden.