How to build a wildlife pond - the lazy way
Choosing the best position for a trouble-free pond
A site which gives a mixture of sunlight and dappled shade is probably the best haven for a varied ecosystem, and reflects natural ponds which are often surrounded by vegetation and teeming with life. The little creatures who'll use your pond will appreciate the shelter and safety of nearby vegetation; and a log pile or a compost heap where hedgehogs might hibernate in winter.
Choose a site which is not too close to any tree roots, or overhung by deciduous trees which will drop leaves into the pond and promote the growth of algae. Evergreens like lavender and euonymus plus densely planted borders surround my pond with plenty of greenery while enabling it to remain relatively clear of leaves.
You can make your pond a shallow depression, thus creating a bog garden where wildlife will come to drink or bathe. If you feel more ambitious, you can allocate sufficient space to enable a variety of depths, a gradual slope for creatures to exit, some shallows for marginal plants; and a border around the edge which can be a mixture of plants and access points for you. A pond of this nature will attract many different species, such as frogs, newts, damselflies, etc.
Damselflies are a joy to behold on summer days
Calculating how much pond liner is needed
A wildlife pond is best to have varying depths, up to about 60cm.
First establish the overall length, width and depth you'd like; then calculate how much lining is required as follows:
Take your length and width measurements, then add twice the depth plus 60cm for the sides (i.e. for a pond which is 60cm deep you'd add 120cm plus 60cm).
See the chart below to get the sizes of lining required for ponds of up to 60cm deep.
Lining required for ponds of up to 60cm deep
lining size = 2.8m x 2.8m
lining size = 2.8m x 3.8m
lining size = 2.8m x 4.8m
lining size = 2.8m x 5.8m
lining size = 3.8m x 2.8m
lining size = 3.8m x 3.8m
lining size = 3.8m x 4.8m
lining size = 3.8m x 5.8m
lining size = 4.8m x 2.8m
lining size = 4.8m x 3.8m
lining size = 4.8m x 4.8m
lining size = 4.8m x 5.8m
lining size = 5.8 x 2.8m
lining size = 5.8m x 3.8m
lining size = 5.8m x 4.8m
lining size = 5.8m x 5.8m
lining size = 6.8 x 2.8m
lining size = 6.8 x 3.8m
lining size = 6.8 x 4.8m
lining size = 6.8 x 5.8m
Delegate the digging
A pond hole doesn't take much digging, because parts of it should be more shallow, but here are some suggestions which will make it easier:
- Mark off the area which will be deepest, then offer the soil and any turf for free on a site like Freecyle, Freegle or Gumtree, for people to come to dig up themselves.
- Enlist the help of friends.. Throw a Pizza and Pints Pond Party as a thank you.
- Look for a local time share or LETS scheme where you could exchange a few hours of help for something less taxing.
- Hire or borrow a rotovator.
- Pay someone to work for 2-3 hours to dig the pond and help lay the lining.
Excavated soil can be used to landscape around the pool (e.g. to raise the edges to reduce the amount of digging required) but pack it down well so it won't subside later. Alternatively, it could be added to a lasagna bed (see my piece on lasagna beds), scattered over existing borders or layered through your compost bin.. (If it's heavy clay, then soak it for a few days and break it down first)
Carving out the best shape and size for a wildlife pond
Although a shallow bog garden is very easy, it's well worth putting in the extra effort to create a wildlife pond with varying depths of up to about 60cm. I think a long thin pond is easier to maintain than a circular one, so my suggestion is that you don't make the deeper parts much wider than 150cm, unless you enjoy getting wet.
When the pond is being dug, you might find that rocky ground gets in the way. If so, just go with the flow and excavate the deeper parts where it's easiest.
To ensure that your pond isn't higher at one side than the other, place a plank across it, top that with a spirit level, then adjust the sides accordingly.
Bear in mind that you'll be adding plants in containers, so it's essential to have flat areas at the bottom and flat shelves around the sides on which to sit your containers of plants. You'll also need to create a gentle slope out of the water, to enable creatures to access it and exit easily, so ensure that you make the top shelf big enough to allow you to add a gradually sloping ramp of smooth stones on top of the lining. See the illustration below for guidance:
Cross-section of a pond
Preparing a pond before installing a lining
The bottom and sides of your hole need to be smooth and free of anything sharp which might puncture your pond liner.
It isn't essential to underline the pond, but I recommend it, as it will help to protect the lining from damage by roots or stones and thus prolong its life.
Firstly, you could spread a layer of soft sand (or newspapers) across the base of your pond, then add your underlining. Normally, a fabric called "geotextile" is used. It needn't be laid as a single piece, so you can cut it and overlap it where necessary. (You could also use old carpet, layers of newspaper or other materials, but they won't be so handy and easy to fit, nor necessarily so effective.)
Choosing a pond liner
There are various options for lining a pond:
- For the lazy gardener, flexible sheeting is probably the easiest option, with rubber being the more natural and durable option and plastic being cheaper.
- Non-flexible PVC or plastic sheeting can be cheaper, but it needs more careful fitting to avoid damage, and the lighter versions are less durable than rubber.
- I personally think that moulded pond liners are the stuff of nightmares to install, plus they don't tend to be very well shaped for wildlife ponds, so I wouldn't recommend one of those. Some say that they prefer moulded liners because herons cannot puncture them, but I've had a wildlife pond for ten years and have yet to see a heron in the garden.
How to instal a pond lining
Unroll the lining across the length of the pond, ensuring that it covers all the shelves and reaches the deepest point of the pool, so it won't stretch and thin at these areas. Then open it out and gradually flip, fold and tease it into position to ensure it's covering all the nooks and crannies.
Once you're sure it's as well positioned as you can make it, you can start to fill in with water (preferably rainwater) which will help to push it into all the nooks and crannies. Adjust the liner as it fills to ensure a neat fit.
How to hide a pond lining with bricks or stones
It's not essential to hide the pond lining, but it's very easy. You can create an edging of rock or brick which conceals the lining completely by placing bricks or rocks on your marginal shelf in front of the lining at the pond edges. (See the cross-section sketch above). Use off-cuts of geotextile liner under the stone to prevent it from weakening the liner beneath it. Remember to add ramped areas for critters to enter and leave the pond.
If you haven't factored space for an area of stone into the original design, as long as you have some spare liner around your pond, you can simply carve a shallow shelf around the edge. Your lining will lie across this shelf and up the vertical face to ground level, where it can be concealed by soil, gravel, flagstones, etc. Protect the lining with geotextile off-cuts then place bricks on top of it. (See the sketch diagram above) You can then fill your pond up to near the top of the bricks or stones. The important issue is to always include some shallow ramps made from pebbles to enable pond visitors to exit the water easily.
Collect rainwater to top up your pond to avoid algae problems
Once the pond is full of water, you can conceal the edges of the liner with soil, and trim off any excess (leaving a generous margin around the pool. (Remember that you could leave the excess in position to create a bog area for further planting). If you're using bricks, rocks or small paving stones to edge your pond, first protect the lining with offcuts of your geotextile, then position your edging on the top of it.
Can I use tap water in a wildlife pond?
When filling a wildlife pond, rainwater is the best option, but tap water can be used, as long as you leave it for several days before introducing plants. When I built my own pond, I used tap water and stocked it with native plants fairly soon afterwards. Tap water contains chemical fertilisers, so there was an initial bloom of algae, but thereafter the pond chemistry established itself, the algae disappeared and my pond remained trouble-free for years.
Topping up the water level in your wildlife pond
Once you have got a nice healthy pond, it's preferable to allow the level of the pond to drop and wait for the rain to refill it naturally rather than promote the growth of algae by adding tap water
You can collect rainwater for topping up your pond by covering basins in plastic with several holes punched in it, then concealing them in the borders near your pond.
An alternative would be to add a gutter and downpipe to a shed roof and collect the water in a tapped container. Always cover the surface so birds and insects don't drown in the water.
What pumps, filters and water-features are suitable for wildlife ponds?
A good wildlife pond stocked with good oxygenating plants does not need costly pumps and filters - it requires very little maintenance at all. Pumps and filters are best avoided, because even those which advertise as being wildlife friendly can pose a threat to the inhabitants of your pond.
If you'd like a waterfall or a little fountain, I suggest that you install one as a separate feature alongside your pond, where it is easy to maintain and won't affect the healthy ecosystem of your pond.
Irises are a beautiful marginal plant for ponds
How to choose plants for a wildlife pond
A variety of native plants should be selected to oxygenate the water, provide stalks for insects to climb out of the water and safe havens for little creatures to hide in. All this will add to the beauty and diversity of your pond, promote a healthy ecosystem and keep your pond virtually maintenance-free.
This is a subject which deserves time and space, so I'll write a separate hub to cover this issue. Coming soon!