Spring and summer are the months when a garden pond earns its keep. Tadpoles turn into frogs, dragonflies patrol the margins and the first water lily bud pushes up through water that is finally, tentatively warm. But the warmer weather also brings blanketweed, hungry fish and thirsty hedgehogs, so a little steady work through the season keeps everything in balance.

March: clearing, dividing and a cautious start

Water is still cold in March and the creatures in it are slow, so move gently. Work from the edges inwards and always leave anything you pull out on the side for a day, so invertebrates can crawl back in.

• Net out fallen leaves and dead plant material before frog spawn arrives. Once you see spawn, only clear what you can reach without wading in.
• Cut back dead marginal stems to about 10cm above water level. Hollow stems are used by emerging insects and amphibians as shelter.
• Lift and divide overgrown water lilies and marginals now, before growth starts. Repot into aquatic compost topped with gravel — never garden soil.
• If a late frost is forecast, float a ball in the pond so gases can escape and wildlife has somewhere to sit if ice forms.

April: feeding plants without feeding the algae

This is the month to give plants a push, but the golden rule is that every nutrient you add also feeds blanketweed. Feed the plants in their baskets, not the water.

• Plant oxygenators such as hornwort, water starwort and water milfoil — roughly one bunch per square metre of surface area.
• Push slow-release aquatic feed tablets into the baskets of established lilies and marginals, one per small pot.
• Avoid using general-purpose fertiliser anywhere near the pond. Even lawn feed washing in from the edge will trigger an algae bloom.
• Never move spawn or plants between ponds. It spreads disease and invasive species. Enjoy what arrives on its own.
• Build or clear a shallow pebble beach at one edge. Frogs, hedgehogs and thirsty birds all need a way in and out.

May: pumps, filters and water quality

Once water holds above about 10°C, fish begin to digest food properly again. Start with a light wheatgerm-based feed and give them only what they clear in five minutes.

Now is also the time to give your equipment a proper service before the summer load builds up.

• Remove the pump impeller, clean out grit and check the cable and seals. A clogged impeller is the most common reason for a weak flow.
• Rinse filter sponges in a bucket of pond water, never tap water, so you do not wipe out the bacteria doing the work.
• If you run a UV clarifier, fit a new bulb at the start of the season. Green water that lingers more than a fortnight usually means the bulb has faded.
• Top up with rainwater from a butt wherever possible. Tap water adds nutrients and hardness, and a small pond can drop several centimetres in a day.
• Keep the water level stable. A submerged pump left running in a shallow pond can drain the wildlife zone without you noticing.

June: shade, shelter and wildlife safety

As the sun strengthens, aim for roughly half to three-quarters of the surface covered in floating leaves by midsummer. A water lily, floating heart or water hawthorn will cool the water, shade out algae and give amphibians somewhere to hide.

• Top up regularly. Shallow margins dry out first, and that is exactly where tadpoles and newt larvae are living.
• Provide easy exits: a gently sloping pebble shelf, a rough plank or a bundle of twigs angled into the water.
• Keep pesticides, slug pellets and chemical algicides well away. A single dose can strip a pond of its whole food chain.
• Twirl blanketweed out with a stick by hand rather than treating it. It is tedious, but it is safe and it removes the nutrients too.
• Check long grass before strimming. Hedgehogs, frogs and slow worms all rest there during the day.

July and August: holding the balance in the heat

The pond is at its busiest and most vulnerable. Oxygen levels dip on still, hot days, and nutrients build up as plants and fish waste break down.

• If fish gulp at the surface in the early morning, add an airstone or fountain and run it overnight. A slow trickle of rainwater also helps.
• Thin oxygenators if they cover more than a third of the surface, but never clear them all — they shelter invertebrates and shade the water.
• Refresh a shallow dish of water on the ground each day for hedgehogs and birds, and keep bird baths topped up.
• Before a holiday, top the pond up, set any pump on a timer and ask a neighbour to leave the fish alone rather than overfeed them.

None of these jobs takes long, and most of them are simply a case of looking before you act. Do them steadily through the season and by late summer you will have clear water, healthy plants and a garden that hums, croaks and flutters from dawn until dusk.