How to build a wildlife pond in your garden

The stages in building a wildlife pond explained

Each stage to build a wildlife pond is explained in easy to follow detail here. 

  • Digging and shaping the hole to make a wildlife pond
  • How to work out the correct size pond liner
  • Fitting the pond liner
  • Finishing the pond and covering the edge of the liner
  • List of pond plants for wildlife ponds
Stage one. Digging the hole
Stage one. Digging the hole

Things to consider before digging the hole for a garden pond.

  1. Can I make a garden pond safe for Small children?   Water is a fascination to children and even a shallow pond in the garden can be a dangerous place for kids. My article here explains how to make a pond safe. Or consider building a small container pond with fountain until the children are older or try a Bog garden.
  2. How much space will I need to build a nature pond in my garden?  A container, a small Belfast sink or a half barrel pond will be big enough to sustain wildlife and can fit into the smallest of gardens. A wildlife pond can be any size you want it to be.
  3. Can I keep fish in a wildlife pond? A pond stocked with koi carp will not sustain wildlife. Wildlife and fish are not a good mix, greedy koi will eat almost everything in site including insects, tadpoles and even pond plants, so if you are building a pond for nature avoid fish. In larger ponds a few goldfish should be OK. The information in this article is not intended as a guide to build ponds to keep koi fish,  they require constant attention, and an expensive, extensive filtration system as they do nothing apart from gulp food and contaminate the water. Much more interesting and fun to watch frogs, newts, pond skaters and dragonflies, and the enjoyment is all free.
  4. Whats the best position for a wildlife pond? Basically anywhere not surrounded by trees or in deep shade. Leaves can be troublesome in the autumn, a few leaves should not be a problem and can be netted out. Shade is a bigger problem as few pond plants will grow well unless there is adequate light. Some shade is necessary and this can be provided by pond plants like water lilies and other floaters. More info further down.
  5. Building a pond in a garden that slopes. Providing the high bank is made so that it doesn't crumble into the pond, ponds built into slopes can look particularly attractive especially with streams or cascades running over the high side. 
  6. What depth should a wildlife pond be? Wildlife ponds need about the same depth (three feet) as goldfish and Koi ponds. But should be shaped with varying depths by forming shelves and ledges, either under the liner or formed after the liner is fitted using stone and clean chemical free soil from the garden. It is also important to form gently sloping sides when digging the hole to allow frogs and newts and insects to enter and exit the pond. Frogs lay their spawn in shallow water and both large and small birds will find it easier to drink or bathe in your pond.
  7. Can I create a nature friendly ponds in a container. Shallower nature ponds about 18 inches deep will still attract and sustain some wildlife. The creatures themselves will decide if they want to set up home. 

Digging and shaping the hole to make a wildlife pond

  • Mark out the shape of your pond using a thick rope trying to make curves as smooth as possible. Don't make the shape too complicated or the corners too sharp as it will be difficult to make your liner fit neatly. Make your pond as big as possible in the space available and avoid deep shade.
  • Form a shelf 9"-12" deep and 12" wide round part of the inside of your pond, to enable you to grow marginal plants in baskets and to provide a suitable place for frogs to lay frogspawn. It is easier to form the shelf as you are digging out and shaping the hole and then lay the liner over it.
  • A wildlife pond should be formed with at least one deep spot, try to get the depth of the deepest bit to about three feet for frogs to hibernate in the mud at the bottom and for planting pond plants that require deep water.  
  • Form gentle slopes from the deepest point up to the shelf or pond edge as entry and escape points for frogs and pond-life to get in and out off the water, this will also enable animals like Hedgehogs and birds to drink and bathe safely. 
  • Stones can be positioned on the shelves to project above the surface to give frogs and other pond life a place to bask in the sun. Natural stones also look good set around the edge of the pond and form a safe habitat for insects.
  • Check the levels with a board and spirit level ensuring the surface of your pond is completely level. Add or remove earth to the banks as necessary patting it down so it doesn't sink later under the weight of the liner and water when you fill the pond.
  • Remove all large stones and roots to avoid damaging the liner.
  • Line the sides and base of the hole with a 1" thick layer of damp sand.

You are now ready to fit the liner

How to work out the correct size pond liner

Rubber liner is more flexible than plastic and I find it the easiest to fit, but it is more expensive than the plastic ones. I also fit a fabric underlay between the liner and the sand. Amazon stock a large range of different pond liners, underlay and sizes.

This is how to calculate the size of the liner required.
Length of liner = twice maximum depth of pond + maximum length of pond + 1m (3' 3") excess.
Width of liner = twice maximum depth of pond + maximum width of pond + 1m (3' 3") excess.

 Puddling clay. An alternative really natural way to line a pond is to use puddling clay.


Fitting the pond liner

This is easier to do on a warm day,  the liner will be more flexible and easier to fit and shape.

  • Roll out or unfold the liner across (not inside) the hole and weigh down the edges with stones to hold it. Be careful not to use very heavy stones or weights as this could rip or stretch the liner
  • Now slowly fill it preferably with a slow flowing garden hose.  As the liner sinks into the hole and the water level rises move the stones backwards still holding the liner to allow the liner to sink slowly under the weight of water into the pond.The liner will stretch to most of the contours, but keep an eye out for creases and sharp curves and fold or shape by hand trying to get the creases folded into corners.
  • At this stage  add about 2 inches of aquatic compost ( compost that is low in nutrients) or clean soil, without fertilisers or pesticides from the garden, to the bottom and shelves of the pond. This is for plants to root in and frogs and other pond-life to hide in and should be allowed to build up over the years with falling leafs. 
  • Leave the water and liner to settle. Check the surface is level and adjust the soil as necessary. Trim excess liner, leaving at least 6" all the way round. 
  • Peg down the liner edge.

Finishing the pond and covering the edge of the liner.

  • I finish and cover the wildlife garden ponds edges by laying grass turf over the 6 inches of liner. To do this cut 18 inch sections from the roll of turf and lay them side by side all around the pond edge with about 4 inches dipping into the water and the rest laid over lightly dug soil. As the grass grows it will make the pond even more natural, especially if you plant or sow wildflower seeds in it.
  • Another simple way to cover the pond edge is to scoop out about 3 inches of soil from around the edge below the liner, lower the liner edge and spread the soil over it. Sow a waters edge mix of grass and wildflowers over the soil. 
  • Local natural stone laid around the edge will look good, be careful though, you don't lay a trip hazard. For safety, you could set the stone on a mortar mix or sink them into the soil and check for level
  • A bucketful of water from an established pond will kick start the culture that will eventually together with the pond plants help keep the pond water clear and healthy. 
  • Stones in the water at the bottom of the pond will give your pond creatures somewhere to hide.  A shallow pebble beach will allow small animals safe access to the water.
  • Tall grasses, logs, large stones set one on top of the other, and planting round the back edge of your pond will encourage insects and animals  and create a hiding place for your amphibious pond life.
  • You have made your own nature pond, all that's left now is to plant some pond plants and wait for the pond life to arrive. You built it and they are coming.
  • You build it and the pond-life will come.  

List of pond plants for wildlife ponds

Pond plants are essential to achieve a correct water balance and provide surface cover in your garden pond. Without them your water will probably resemble pea soup, as algae will grow prolifically.  Plant foliage absorbs carbon dioxide and minerals from the water which 'starves' the algae. About half of the water surface should be covered with foliage to achieve this balance.

Pond plants fall into four basic groups. Each is important to the health of your pond. The groups are oxygenators, floaters, marginals and deep water aquatics. 

Floaters.

 Floaters are pond plants you drop into the pond. Their roots are submerged and their leaves and stems float either on or just below the surface. They provide surface cover. Many of them sink and overwinter at the bottom of your pond. Water hyacinth is a flowering 'floater' but only in a good summer. 

Other floaters include frog-bit, water lettuce and water soldier and fairy moss. Duck weed is also a floater, it is invasive and best avoided. Once you have duck weed established in your pond, you will never get rid of it. 


Deep Water pond plants

Deep water plants need to be planted at least a foot deep. Their leaves help to shade the pond and keep your pond life cool, provide shelter and help keep the water clear by limiting the sun's rays.  

Water hawthorn is fragrant, long flowering and will tolerate moving water and some shade. Golden club needs to be planted in a deep tub. Has distinctive yellow and white flower heads. 

Once again to many to list here its worth a visit to a local pond center. The water lily in the picture is one I have planted in my pond at home.


Marginal pond plants.  

Marginals are planted on the margins of the pond. They include Marsh marigolds, pickerel weed and many more. Plant them on the shelf we built around the pond. 

They look good and provide some protection for your frogs and other pond creatures from predators. The Mix of Marginal pond plants in the picture are also perfect for bees & other pollinating insects.

I  remove marginals from the baskets, keeping the root in as much compost as I can and plant them on the shelf held down by stones, looks more natural.

Oxygenating pond plants for natural ponds. 

Oxygenators are very important for keeping the water clear. Their roots and stems are submerged and usually the leaves are submerged as well. They are often bought in bunches. You will need one bunch for each 3 sq. ft. of surface area. Most oxygenators do not flower, but two exceptions are water violet and water buttercup.

Water milfoil is ok for a small pond. Willow moss is evergreen and slow growing. Hornwort and curly pond weed (elodea crispa) are effective oxygenators.

The pond oxygenting plant in the picture is not invasive so Ideal for ponds of all sizes, probaly the reason it is the top seller on amazon.


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