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How-to make a garden pond
A garden pond can transform the feel of a garden, adding colour, light and movement. If you include a pond pump you can enjoy the soothing sound of moving water too. Birds love them, and their reflective surfaces fill the garden with light on even the dullest day.
There are several different styles of garden pond, the one you opt for depends on the style of your garden and the space you have available.
Square, circular and rectangular ponds are ideal for formal gardens, while irregular-shaped ponds like the popular kidney-shape look best in less formal settings. All ponds attract visiting wildlife, and if you design and construct it with this in mind, you can create a perfect home for frogs, insects and birds.
Where to put a pond?
It’s really important that you choose a good spot for your pond. Otherwise, you might run into problems and you’ll need to spend much longer maintaining it. Try to avoid areas that are in deep shade or near overhanging trees. If you’re sinking the pond into the ground, make sure the site is free from underground obstacles, like drainpipes and cables.
You also need to think about how the pond will fit into its surroundings. Choose a position where there’s space to plant a border along one side of the water feature to provide a natural transition into the rest of the garden.
Try imagining what the reflections might be like on the waters surface when you’ve built your pond – it’ll help you choose a spot.
What size pond to have?
As a general rule, larger ponds are easier to look after – as long as you’ve put it in the right place. If you want a pond filled with aquatic plants and fish you’ll need a surface area of around 5m² (that's about 7x8ft) for it to be self-sustaining. The deepest area should be about 60cm, with 15-cm deep shelves running along the edges where shallow-water plants can be grown.
If you want something smaller, then be prepared to maintain your pond regularly or forget about stocking it with fish. Plant-only ponds can look really attractive and still be home to a wealth of wildlife. In fact, if you want a wildlife pond, it’s important not to add fish to the water because they will eat many of the creatures you are trying to attract.
How to calculate the size of the liner needed
If you’ve decided to use a flexible liner (like a plastic sheet) for your pond you’ll need to work out which size of liner to buy. The easiest way to do this is to use the following method:
2 x maximum depth of pond + maximum length of pond = length of liner required
2 x maximum depth of pond + maximum width of pond = width of liner required
So, for a pond that is 4x3m with a maximum depth of 50cm you would require a liner that is at least 5m by 4m.
What kind of liner to use?
There are basically two types of liner you can use – flexible and rigid. Flexible liners are available in various materials including PVC, butyl rubber, LDPE and polythene. Rigid liners are either made from fibreglass or a hard plastic.
Using a flexible liner
Polythene is the cheapest option, but it will only last for a few years, plus it’s easy to puncture. The rest are all much stronger and will last three to four times longer. Butyl rubber is the best, lasting up to 20 years, but it’s the most expensive.
Installing a flexible liner:
1. Use a hosepipe to mark out the size of the pond on the ground. Dig the whole area down to the depth of 20cm. Make the sides slightly sloping towards the centre of the pond.
2. Then mark the deep-water areas and dig out the soil in the middle of the pond to a depth of about 65cm, again making sure the sides slope slightly.
3. As you dig, check that the top edge of the pond and any shelves are level using a piece of timber and a spirit level.
4. Once you’ve finished digging, remove any stones sticking up into the hole before lining all surfaces with a 5cm layer of damp sand.
5. On a warm day lay the pond liner out over the prepared hole and weigh down the edges with stones. Slowly fill the pond with water from a hosepipe, circling the liner and gently tugging at the edge to remove any creases. When the water is 5cm from the top of the pond, turn off the tap and leave the pond to settle for 24 hours.
6. Trim the liner to leave about 15cm of overlap around the pond – then add the edging (like stones).
Using a rigid liner
There’s not much difference between the plastic and fibreglass rigid liners. Both are very strong and will last about 15 years – so the base you choose depends on what shape and size you want.
Installing a rigid liner:
1. Stand the liner where you want to put it, and mark the position of the edges (liner shape) on the ground with sand or spray paint.
2. Make a second mark about 30cm further out to indicate the area to be dug.
3. Dig the whole area down to the depth of the shelf. Then dig an extra 5cm down to allow for sand. Make sure the sides slope slightly towards the centre of the pond.
4. Then mark the deep water areas and dig out the soil in the middle of the pond to the maximum depth of the liner, plus 5cm as before. Don’t forget to make sure the sides slope slightly.
5. Once you’ve finished digging, remove any stones sticking up into the hole before lining all surfaces with a 5cm layer of damp sand.
6. Stand the rigid liner on the sand and check the levels of the liner. When it’s in the right position, wedge pieces of wood around the sides to hold it steady. Then carefully fill in any gaps around the sides of the pond, while slowly adding water to the liner from a hosepipe.
7. Make sure there are no air pockets by pushing down on the liner (pay particular attention to the areas under the pond shelves). Check the liner is still level and make any minor adjustments if needed. Once all the gaps around the liner are filled and the pond is full of water, leave it for 24 hours before adding the edging.
Edging your pond
A pond needs a neat and practical edging to make it attractive. You can edge a pond with a range of different materials – the one you choose depends on the style of pond you’re trying to create.
Formal ponds. These need a formal edging. The easiest way to achieve this is to use paving slabs and mortar – trapping the edge of the liner underneath. For the best effect, make sure the paving overhangs the edge of the pond by about 5cm to help hide the liner from view.
Informal ponds. Irregularly shaped ponds look best using paving of different sizes or bricks that can be laid on edge to follow the sweep of the curve. If you use paving slabs or bricks you will have to lay the edging material on mortar so it traps the edge of the liner underneath.
Wildlife ponds. A wildlife pond needs a natural-looking edge that allows easy access for you and visiting creatures. To do this you can try using pebbles, turf or plants.
If you use turf, remember it cannot be treated with chemicals as it can contaminate the water – not good for fish. It’s also worth including a safe place along one edge to view the wildlife – timber decking works well because it blends in, but paving or bricks can also look nice.