Spring is the season when a garden pond wakes up. Frogs return to spawn, oxygenators begin to pearl, and the first waterlily leaves push through the surface. But the milder weather also exposes problems that winter hid: blanketweed, cloudy water, a pump that hums but does not flow. A few simple jobs now will save you hours later and give wildlife a healthy start.
Begin with a gentle tidy, not a deep clean
The biggest mistake at this time of year is to empty and scrub the pond. That destroys the tiny ecosystem you have spent years building. Instead, work with the pond while it is still cool and the inhabitants are slow.
- Remove debris: Use a fine pond net to lift leaves, twigs and dead plant material from the surface and from the bottom where you can safely reach. Pay attention to corners where wind pushes rubbish.
- Leave the sludge: A layer of silt is home to larvae, worms and beneficial bacteria. Remove only the excess if it is smothering plants or filling the pond.
- Trim dead foliage: Cut back dead stems of marginals and grasses to just above the waterline or crown, using sharp secateurs. Do not cut into new green growth.
- Watch for spawn: If frogs or toads have laid spawn, work around it. Do not move it to another pond, as this can spread disease and invasive plants.
Check pumps, filters and pipework
After a winter of frost and falling leaves, your pump and filter need attention before the growing season speeds up. A blocked pump can burn out, and a neglected filter will struggle to clear spring algae.
- Clean the impeller: Unplug the pump first, then open the housing and remove any grit, blanketweed or snail shells wrapped around the impeller. A soft brush and clean water are enough.
- Inspect hoses: Look for splits, kinks and loose connections. Flush them through before reconnecting. A leaking hose can drain a small pond surprisingly quickly.
- Restart filters gradually: Clean filter sponges in a bucket of pond water, not tap water, to preserve the bacteria that break down fish waste. Replace only what is falling apart.
- Check UV bulbs: If your filter uses ultraviolet light to clear green water, a bulb older than a year is probably spent. Replace it now so it works when algae first blooms.
Test the water and top up wisely
Spring rain is often acidic and nutrient-rich, while winter run-off can carry garden chemicals into the pond. Testing now gives you a baseline before you add plants or feed fish.
- Test for pH, ammonia, nitrite and nitrate: A simple liquid test kit is more accurate than strips. Aim for stable readings rather than chasing a perfect number.
- Top up with rainwater: Use water from a butt or water butt rather than tap water where possible. If you must use tap water, add a dechlorinator and top up in small amounts.
- Add oxygenators: Hornwort, water milfoil and curly pondweed compete with algae for nutrients and shelter small creatures. Drop them in weighted bunches.
Divide and rejuvenate pond plants
Pond plants are vigorous, and by spring many will have burst their baskets. Dividing them now keeps the pond balanced and encourages fresh, floriferous growth.
- Waterlilies: Lift the basket when you see new leaves. Cut the rhizome into sections with a sharp knife, keeping a growing point on each piece, and repot into aquatic compost in a mesh basket.
- Marginals: Irises, marsh marigolds and reeds can be split with a fork or spade. Replant a smaller clump and pass the rest to a neighbour or another part of the garden.
- Oxygenators: Thin out dense mats by hand, leaving enough to cover about a third of the pond surface. Do not compost excess in the pond, as it will rot and foul the water.
Plant up margins and waterside borders
The edges of a pond are just as important as the water itself. They hide the liner, shelter wildlife and soften the transition from water to garden.
- Choose right plant, right place: Bog plants such as ligularia and rodgersia like damp soil, while marginals like flowering rush and water forget-me-not want their roots permanently wet.
- Use aquatic compost: It is low in nutrients, so it feeds plants without encouraging algae. Top the surface with gravel to stop fish and birds disturbing the soil.
- Mulch waterside borders: A layer of well-rotted organic matter helps retain moisture, but keep it back from the water’s edge so it does not wash in and feed blanketweed.
Look after fish and welcome wildlife
Fish are still sluggish in early spring, and their immune systems are low. Wildlife, meanwhile, is actively looking for food and shelter. A light touch is best.
- Feed sparingly: Wait until the water is consistently above 10°C before offering food. Start with a few wheatgerm pellets and remove anything uneaten after ten minutes.
- Create a wildlife ramp: Place a gently sloping stone or piece of untreated wood at the edge so hedgehogs, frogs and small mammals can climb out if they fall in.
- Leave a wild edge: A patch of longer grass, a log pile or a shallow pebble beach gives insects, amphibians and birds a place to drink, hunt and hide.
Work through these jobs on a mild, dry day and your pond will reward you with clear water, healthy plants and a chorus of frogs before the end of spring.
