Why a small pond earns its place in a glen garden

A pond does not need to be grand. Even a basin barely wider than a wheelbarrow can transform a sheltered corner of a Scottish garden, and in a glen setting it quickly becomes the busiest patch of ground you own. Common frogs arrive to spawn in late February or March, often before the last snow has left the hills. Damselflies and dragonflies hunt over the surface through summer, swallows and house martins skim low to drink, and blackbirds and hedgehogs come to the edge to bathe and drink quietly at dusk.

There is a practical side too. Frogs and their tadpoles take a serious toll on slugs, and a pond brings in the predatory insects that keep midges and other small flies in check. In a rural garden surrounded by rough pasture, bog and birch scrub, a small native pond simply joins the dots between habitats that already exist around you.

Choosing the right spot

Position matters more than size. Aim for somewhere that gets sun for at least half the day, but is not scorched from dawn to dusk, and where the prevailing south-westerly wind is broken by a hedge, wall or shrub. Shelter keeps the water warmer, which speeds up frog development and encourages insects.

Keep a few things in mind before you lift a spade:

• Stay well clear of willow, birch and rowan roots, which will find any puncture in a liner.
• Avoid the bottom of a slope where nutrient-rich run-off from the garden or neighbouring fields will drain in.
• Leave a strip of long grass or a low hedge nearby so amphibians have cover on their travels.
• Check for buried cables, drains and water pipes before digging, and think carefully about young children if the pond will be unfenced.

Digging and shaping a gentle edge

For most gardens, roughly 1.5 to 2 metres by 1 metre is plenty, with a depth of 45 to 60 centimetres in the centre so the pond rarely freezes solid. Build in a shelf at about 20 to 25 centimetres deep along one side for marginal plants, and leave the opposite side as a shallow, sloping beach just a few centimetres deep.

That beach is the single most valuable feature you can create. Frogs, hedgehogs, birds and thirsty bees all need a way in and out that is not a vertical wall. Shape the edge so it wanders slightly rather than forming a neat oval, and bank soil up behind it to hide the liner.

Line the hole with old carpet, sand or a purpose-made underlay, then butyl or EPDM rubber. Fold the edges over, tuck them under turf, and weight them with flat stones, logs and moss. Fill the pond with rainwater collected in a butt if you can. Tap water carries nutrients that feed algae, so it is worth waiting for a few good showers rather than reaching for the hose.

Planting with natives

Plant once the water has cleared, using baskets of heavy loam rather than rich compost, which leaks nutrients. Aim for roughly a third to a half of the surface covered in growth, no more, so there is open water for birds and insects.

• Oxygenators: hornwort and curled pondweed, which sit below the surface and keep the water clear.
• Marginals: marsh marigold, water mint, water forget-me-not, lesser spearwort and soft rush.
• Statement plants: yellow flag iris and bogbean, both best in a basket as they spread eagerly.
• Edges: ragged robin and purple loosestrife nearby, left uncut into winter.

Avoid invasive non-natives such as parrot's feather, floating pennywort and water fern, which can escape into burns and lochs. Please also resist adding goldfish. They eat tadpoles, stir up silt and turn clear water green.

Making the edges work harder

The wildlife value of a pond is often in its margins. Leave a pile of stones and a couple of rotting logs on the sunny side for beetles, newts and frogs to shelter under. Let a patch of grass grow long beside the water, and plant a low shrub or two within a few metres so emerging damselflies have somewhere to climb and dry their wings.

Birds need a shallow shelf or a large stone breaking the surface to bathe safely. If you have hedgehogs, a gently sloping ramp of stones or a piece of rough timber will let them drink without risk of falling in.

Looking after it through the year

Spring: watch for frogspawn from February onwards and leave it where it is. Resist the urge to move it between ponds, which risks spreading disease. Summer: top up with rainwater during dry spells and pull blanketweed out by hand rather than treating it with chemicals. Autumn: net the pond for a fortnight if leaves are falling heavily, then leave the margins standing for overwintering insects. Winter: never smash ice, as the shock can kill frogs resting in the silt. Float a ball or rest a warm pan on the surface to keep a gap open.

Avoid insecticides, slug pellets and fertiliser anywhere near the pond, and empty out excess silt only every few years, in late autumn, always leaving a layer behind. A new pond often looks bare for a season or two. Give it time, and by the third spring it will be croaking, buzzing and alive.