A pond can attract a greater variety of wildlife than perhaps any other single feature in the garden. It provides a breeding space for frogs, toads, newts and dragonflies as well as a habitat for a host of other creatures from pond skaters to water snails. A pond that is shallow at one end will also provide bathing areas for birds and a watering hole for hedgehogs.
One of the aims of Living Gardens is about trying to create essential corridors for wildlife to move between habitats. In the same way, a series of ponds in a neighbourhood creates a vital link for amphibians to move through our fragmented landscape.
Building a pond
Remember, although of course it is preferable to have a large pond – a small pond (even a sunken sink) is better than no pond at all. Ponds can be made at any time of year, but they will establish more quickly if created in the autumn. This timing allows the pond to fill with water over the winter period and settled in time for spring, when a range of animals can benefit from the habitat.
Position the pond in a sunny place that is away from overhanging trees. Building a pond that is too close to deciduous trees can mean that in autumn the pond can become choked with leaves . Decaying matter, such as leaves, can absorb oxygen and make water stagnant.
It is also important to link your pond to other garden features. The best Living Gardens contain a mosaic of habitats that species can move through easily and utilise. Having long grass, bushes or piles of logs or rocks will provide shelter and link to these other non-water habitats.
There is no such thing as the perfect pond, but it is good to have:
• A minimum area of four to five square metres.
• Lots of shallow areas less than 30cms
• One area with a minimum depth of 60cm, so that part of the pond can be used by hibernating amphibians.
• Shallow, sloping areas to allow birds and other animals easy access.
• A range of depths to provide appropriate habitat for different plants and species.
• A marsh or bog area.
Digging a pond
1. Mark out your chosen shape with string, a hose pipe or line of sand.
2. Dig out the shape to a depth of about 60-100 cm. Start at the edge and work in. Save any turf to lay along the edge of the pond later.
3. Create sloping sides that support a range of plants and allow animals to get in and out easily.
4. Create varied shallow margins from 1-30 cm to suit different marginal plants. This area will be warmer and encourage frogs and toads to spawn. It will also be a stable edge for mammals to drink from.
5. Vary the profile. You can create soil shelves as you dig or build ledges from rocks or stones after you have laid your liner.
6. Add a shallower boggy area near the pond edge for species to migrate into.
7. Remove roots, stones and rubble from the hole and firm the soil down.
8. Cover the hole with a 3cm layer of builder’s sand followed by an under liner, such as a polyester sheet or old carpet
Add a liner
1. Start at one edge and unroll the liner across your pond.
2. Make sure the liner overlaps the edges of the pond and secure it with rocks or bricks. The length of and width of the liner should be that of the pond plus an additional 60cm to overlap the edges.
3. You could now add another under liner on top of the base liner for extra protection.
4. Fill the pond with water, ideally rain water collected in a water butt. The water will press the liners into shape.
5. Cut any excess liner (any liner exceeding the 60cm overlap) and tuck the edges under varied materials, such as stones, a pebble beach, large flat rocks, turf, logs or paving slabs.
There are several materials which can be used to line a pond, such as clay, concrete and pre-formed linings. The latter are likely to have sides that are too steep for wildlife, and which prevent the build-up of silt. The best solution is probably a flexible lining. The options are polythene, PVC, or butyl rubber. Polythene is the cheapest; butyl rubber is the most expensive, but it is probably the most durable.
Stocking your pond
After going through the effort of digging your pond, it’s important to stock it with the right plants. Here is a non-exhaustive list of some of the native species:
|Plant type||Common names|
Usually submerged plants. Some native species can be fussy especially if pond water quality is poor, but these are some of the most tolerant.
Common water starwort
Plants whose leaves float on the surface. Some of the plants may be rooted, but others float freely. The leaves provide shade for the water below reducing the build-up of algae. They can also act as platforms for viewing, courting or mating for a variety of insects.
Yellow water lily
White water lily
Plants with erect stems and leaves, which emerge above the water’s surface. These are important for dragonfly nymphs to crawl up, before they become adult flying insects.
Plants that need to grow at the shallow edges of the pond. Some need to be permanently in a few centimetres of water, whilst others will tolerate periodic drying out.
|Marsh or bog plants
Wetland plants that grow near the water’s edge. Their requirements vary from those that must be in permanently wet soil, to those which need moisture retentive soil but do not tolerate being waterlogged.
Great hairy willow-herb
Rushes and sedge
But please avoid the following the invasive species:
• Parrot’s feather
• Floating pennywort
• Australian swamp-stonecrop/New Zealand Pigmyweed
• Water fern
• Curly waterweed
• Water primrose
• Water hyacinth
• Water lettuce
Not only can these species over-run your pond, there is a risk a tiny fragment could get into other wildlife ponds in the area. (insert link to pond section)
Maintaining your pond
Once established, your pond should need relatively little attention, but there are a few simple steps to make sure it remains a haven for wildlife species.
As soon as your pond is full it can be tempting to take frogs, spawn or other amphibians from pre-existing ponds to speed up the ‘wilding’ process. But, as well as being potentially illegal, you could be transporting amphibian disease or small fragments of invasive plants into your pond. Instead be patient and wait for word to get round that there’s a new pond in the neighbourhood. It won’t take long before frogs, toads and newts discover your garden.
The introduction of fish into wildlife ponds is generally not advised, as they can eat smaller animals, including spawn and mayfly larvae. It is recommended that fish are only introduced into wildlife ponds larger than 10,000 litres (4x2m) and then only one fish per two square metres of surface area.
Dead organic matter
The build up of fallen leaves and dead vegetation at the bottom of the pond can cause the water to turn brown, as all available oxygen is used up by the decay process. Eventually, a layer of silt accumulates, which makes the pond shallower. This silt layer can be a useful feature for overwintering invertebrates and hibernating frogs. You should not de-silt more than once every five years, unless you have a pollution problem. The best time is in autumn before animals go into hibernation and after plants have finished flowering.
After a while some pond plants may become too abundant. These can be pulled out or divided once every year or two years, reducing their presence by about one fifth to one third/one half. This should be done in the autumn before minibeasts go into hibernation. Some plants can be grown in pots, which limit their spreading. Aim to make sure that between 10 and 30 percent of the pond surface is open for 60 percent of the plants present.
Remember to leave vegetation and dredged material on the banks of the pond for a few days so that minibeasts can escape back to the pond.
As some amphibians may hibernate at the bottom of your pond, it is important it does not become completely frozen solid in the winter. Ponds deeper than 60 cm are usually safe and amphibians can tolerate very low oxygen levels. However, they will not survive if the pond becomes completely deoxygenated.
To stop this from happening, make sure you clear any snow off the ice to allow light to penetrate through. To keep open water, float a tennis ball in the pond but avoid using hammers and boiling water to break-through ice – it is likely to damage plants and wildlife.
Ultimately good water quality and allowing plenty of submerged plants to grow is probably the best way to ensure your pondlife survives through the winter.
During the summer months it is natural for the pond level to decrease. This is not something that necessarily needs correcting as many animals and plants need areas of exposed mud and silt to set seed or lay eggs. If you feel the water is very low and that the pond needs to be topped up, try and use rainwater from a butt and refill gradually to prevent a massive change in the pond’s temperature.
Tap water is not recommended as its characteristics can unbalance the chemistry of the pond and cause algal blooms.