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Build & plant a pond in your garden
Understanding how to build and plant a pond & bog area from the beginning will make it easier to create a successful finished focal point in your garden.
Buiding a pond - siting the pond
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Why do you want to build a pond? Is it for fish, wildlife, plants or as a focal point?
1. Siting the pond.
This decision will affect the style of the pond and its position within the garden - a wildlife pond will be a more informal shape and further down the garden and a fish pond or patio focal point likely to be a more formal shape, possibly raised up not dug down, and nearer the house. A patio container pond needs the same thought process and more detail is available on the container ponds page.
Considerations:
1. a raised pond may be safer for children and give an edge for an elderly person to sit on
2. electricity - for pumps, filters, waterfalls or fountains. The supply will need to be planned in.
3. the position of underground services - sewers, pipes, cables.
4. the pond should not be in a part of the garden in the shade from buildings or trees.
Choose a spot with about 6 hours sunshine a day if you want waterlilies and Iris to flower but a pond in part shade can have advantages as the water will remain cooler and the pond will be less likely to have algae bloom and can be planted with foliage interest plants.
Check whether your site is level. If possible surround it on one or more sides by planting from a moist habitat/bog garden or flower bed to give a visual backdrop to the water. A rockery or sloping cobble beach may help on a sloping site or 2 smaller ponds linked by a stream.
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Build a pond - designing the shape and size
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2. Shape - either informal or formal shapes should be marked out on the ground so you can view the positioning and check for access around it. View from inside and outside the house and consider the affect of any slope on the ground and any curves to the pond edge. Build a sloping shelf cobbled exit on at least one side of the pond if you want wildlife creatures.
3. Size - make the pond with as large a surface area as your space allows. By the time you have finished and included the edging the water area of the pond always looks smaller than you expect. It is also easier to maintain water temperature and balance in a larger rather than a smaller surface area pond.
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Build a pond - digging it out
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4. Dig the informal and wildlife pond to a depth of 60-75cm(2ft-2ft 6") with a number of plant shelves at different depths - approx 15 & 30cm(6" & 12") below finished water height - as wide as possible to accomodate the different aquatic marginal plant species. Cut across the curves to give wide spaces - try not to build a rim of shelves around a larger surface area of deeper water as this will be unbalanced when you come to plant.
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Allow for an edging shelf to contain rocks/cobbles or other edging materials outside the area of planting shelves inside the pond liner. The depth of this should be in proportion to your pond size 5-15cm (2 -6") dependant on the size of the edging materials you are planning to use. The rocks or cobbles will sit on a shelf within the linered area below the finished water level and should protrude above the water giving a method of escape for the wildlife. The edging of the pond is also critical visually to link the pond to the rest of the garden. |
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Showing edging shelf with rocks being built up from a shelf below finished water depth |
Rocks and stones protruding above water level - holding the liner upright. No liner visible. |
Finished pond edge of stones or rocks blends the pond into the rest of the garden |
Or construct a formal raised pond from bricks and blocks either wholly or partially above ground. Build 2 lines of blockwork built on foundations - the inner line could be block as it will not be seen and the outer line should be a facing brick chosen to match your property or patio area. As long as you are not planning a koi pond you only need to build to a depth of 60 - 75cm(2ft - 2ft 6") and create shelf areas within the pond at depths of 15cm and 30cm (6"and 12") below finished water height for plants but being a more formal shape shelves can go either in the corners or along the edges. Make them cover one quarter of the surface area as formal ponds tend to have more waterlilies and less marginal plants and they can have fish. The inside line of block work needs to finish one face brick depth shorter than the outer line of bricks. To accomodate plants in a koi pond a shelf area can be created at one depth with brickwork on the deep water edge of the shelf that allows small fish and water flow through but keeps the larger fish away from the aquatic water plants.
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Showing internal blockwall & an external decorative wall finished one brick higher |
Finished brickwork with liner trapped over top of block wall by extra line of decorative brick |
Two walls of brick with liner in between capped off with coping stone. |
In both cases the finished pond surface must be level - not by eye but using a spirit level otherwise liner will show at one side or another and spoil the look.
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Build a pond - lining the hole
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5. Underlining - After making the pond profile and removing any sharp stones the hole should be lined with an underlining - geotextile. This will uphold the guarantee for the liner you use. This is purchased as 2 metres wide and you order as many linear metres as you need. This does not need to be laid in one piece so you can patch some corner areas from the overlap cut from another corner - geotextile only needs to be one thickness.
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6. To retain the water use a liner. There are many choices of liner materials but 2 good alternatives to consider are butyl - available in different thicknesses, can be heavy to work with but stretches nicely around curves, available with a 30 year guarantee. Or woven polyethylene which also carries a 30 year guarantee but is a cheaper initial purchase, is lighter to work with but has no stretch so requires careful placing and folding into curves and corners. |
To calculate the size of liner needed - measure the overall length, width and depth of the hole. Double the depth to allow for the sides of the pond and add 60cms(2ft). Add this figure to both the length and width of the hole and that will give you the size of liner you need to buy.
7. Electricity - needs to be fitted correctly by a qualified electrician and a certificate received. If they connect an outdoor power socket then pumps for filters, fountains and waterfalls can be used. Solar powered pumps and fountains are becoming more popular and avoid the need for electrical installation.
8. Fit the liner to the hole allowing enough material on all sides and start to fill with water. This will weigh down the liner and you can start to fold or stretch the material into position. Make a small number of large folds in the corners rather than a large number of small folds along a curve. Make sure that the 'behind' side of any fold is always as high as the finished water height or one low fold will forever dictate the maximum height of water your pond will hold. In the informal pond shape the liner will extend over the edging shelf and finish placed vertically up to the top height of that shelf held in position by the placing of rocks or cobbles piled up against it. That shelf area will fill with water to cover about half of the depth of the edging materials.
In the formal pond the liner will be placed inside the hole and horizontally over the shorter inside block work and continue vertically to the top of the outer layer of brick. Be very careful with the corner folds checking that all edges of liner are up to the top of the brickwork. The inside wall can then be made up to the same height as the outside by mortaring an outside decorative brick onto the liner. A coping stone would be added to trap the liner on the top of the 2 layers of brick. The brick and mortar that will be in the water will need sealing with a waterproof sealant to prevent leaching.
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9. Do not trim the liner back until the pond is full of water and the edging is satisfactorily in place wedged between two upright surfaces and you have checked |
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Build a pond - using a preform pond
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Preform - The alternative to working with a liner is to purchase a preformed fibreglass pond but check carefully for shelf variety and the proportion of deep water to shallow shelf area before you purchase. Always measure your space before going to the Garden Centre so you know exactly what width and length will fit your chosen space. It is easy to be misled looking at an empty pond out of situ. |
Fitting the preform into the ground can be more tricky than you thought - mark out the profile of the pond and its shelves
on the ground and dig as near as possible to the correct shape so that the preform sits snugly in the hole. Protect the
pond with a layer of sand and bed the pond in so that it is level. Start to fill with water and place a spirit level over the
top edge. As the water starts to weigh down the pond correct the level if neccessary while backfilling the space around the preform shape with sand.
The preform pond has a horizontal rim around it which is hard to hide or camouflage into the rest of the garden and the water can only fill as high as the rounded top edge whereas in the liner pond with an edging shelf described above the hard lip of the pond can be disguised with softer materials on the edging shelf.
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Build a pond - using a contractor
Build a bog garden around your pond
Create an extended habitat area for wildlife to the pond that will keep them protected and give you a visual backdrop to the water area. If this area can maintain damp conditions then it mimicks the edge of natural water that gets progressively drier as you move away.
1. You can create an area that can be kept moist or wet by digging out 2’ of soil in a straight sided shape and lining the hole with cheap lining material like builders damp proof membrane. Add 3” depth of gravel to the base for drainage and then puncture the membrane with a fork once every square metre This will allow some drainage but keep some moisture in the soil.
2. Refill the lined hole with good soil and humus rich compost and cut the liner off at the top of the hole so the area blends into the rest of the garden. This area can then be kept as wet as you like by watering from a porous or leaky hosepipe that will constantly drip when attached to a tap or water butt. This bog garden will provide protection for wildlife species and you will find that by encouraging frogs to the area they will protect Hosta’s and other plants eaten by slugs.
3. Plants for the moist/bog area can be chosen for a shaded site or a sunny one. Use the selection on our moist and bog plant pages but be aware that some moist species can handle less moisture than others.
Plants can also be selected to cope with more water in the soil (waterlogged in winter) defined as wet mud. The defenition of wet - if you dig a hole to a spades depth and it fills with water then the plant roots will be sat in water and the soil is wet. Wet soil needs to be planted with pond plants as their roots are adapted to cope with having water around them.
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Planting a pond
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Our marginal aquatic plants can be placed immediately into your pond or patio container pond as they are already rooted in aquatic compost in open mesh baskets. You do not need to purchase any baskets or compost and do not have the worry that bareroot pieces will 'float up' when you lower the basket and plants into their position in the pond.
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Images show pond plants in 11cm baskets.
Plants may need to be cut down in the latter part of the season to allow them to fit into a box for dispatch.
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Plant grouping - The wider shelves in the informal pond allows plant grouping to look natural. The aquatic pond plants are placed on the shelves in their baskets in groups so that an upright plant can be softened by a rafting plant at its feet. If you have built a large pond that needs to look mature quickly then plant 3 of each variety into a contour basket and fill with aquatic compost or gravel. Using gravel makes the contour heavier and is useful to stop tall plants blowing over in the wind. |
It is more successful if you keep aquatic pond plants in baskets rather than planting them all directly into mud on the shelves as the vigorous plants will take over the entire shelf area and the less vigorous plants will be swamped. If you are planting into a clay lined pond you would remove the basket and push the plant directly into the clay at the right depth.
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Planting the marginal shelves - shelf 0, shelf 1, shelf 2
Planting the marginal shelves - Pond plants
When you built your pond you have made sure you create the right depth shelvings into your construction. By checking the depths of water preferred by different marginal pond plants you like you will put in the correct ratio of pond shelves.
Planting depth measurements given for each plant are from the top of the basket to the water surface level.
You need to take into account the depth of the basket to calculate how deep the plant will be in the water when placed on a particular depth shelf. Basket heights: (9cm = 3", 1 litre=11cm/4" and 2 litre=15cm/ 6" tall). Water depth is vital to marginal pond plants - too deep and one variety will not thrive, too shallow and some varieties will not receive the frost/ice protection over their crowns that they would receive from deeper water.
Shelf 0: Plants that sit with their crowns at water level: These plants will sit between cobbles or rocks and will be happy with their roots in water but with little or no water over their crowns. These plants could also grow in wet mud in a wet bog garden or on a stream edge with their crowns exposed above water level. Some of these plants can also grow on a 15 - 20cm(6-8") shelf.
Shelf 1: Plants for a shallow 15 - 20cm(6-8") shelf: These marginal shelf plants can be divided into 2 types - those that spread horizontally across the water - rafting plants, and those that spread vertically up and out of the water. Your pond should contain a mix of both to create the habitats different wildlife will enjoy. These plants are listed in the pond plant pages as accepting up to 10cm(4") of water over the top of the basket. If you have dug the shelf too deep - try replanting the plant into a taller basket so that the top of the basket is at the correct depth.
Shelf 2: Plants for a deeper 25-40cm(10-16") shelf: These plants will enjoy a deeper shelf that will place the crown of the plant in water throughout the winter without risk of ice penetrating the pond to that depth.
Potted aquatic pond plants will quickly add foliage, colour and habitat for wildlife to the marginal pond area. Marginal pond plants can be decorative - by creating the mood of the pond - either creating a formal setting by planting one large basket in each corner of a regular shaped pond or a more informal, natural look where the plants are grouped together in mixtures of shapes and textures as in nature. The marginal aquatic plants around the pond look better in groups than in single baskets placed in lines. These aquatic pond plants help to develop the setting that allows the clear reflective water to show inside this frame. As a guidance we recommend a minimum of 3 x 1 litre marginal aquatic baskets per metre length on a shelf, with more if the shelf is wide or if a full look is required quickly.Pond plants appreciate sunshine and need nutrients to thrive and after a season need feeding with a pond plant fertilizer.
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If you have taken over a pond with no shelves in its construction but want to plant marginal aquatic plants in it you will either need to create a shelf system with bricks or plant up our floating planting islands that float the crown of the plants on the water surface. These will use plants from shelf 0 category. |
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Planting deeper water areas - shelf 3
Planting schemes available for ponds
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If you are unsure what to order then let us help.
Order a planting scheme - we will send you a collection of plants so that you will receive a balanced combination of plants for a choice of shelf depths, choice of growth habits and seasonal interest. |
You can choose a British Native planting collection for 3 pond sizes or a more colourful Pond Starter selection which will include non-native plants ie. Iris available in purple or plum rather than the Native Yellow Flag Iris and waterlilies in red, pink or yellow rather than the Native white.
See Planting Schemes page 2 for a selection of sizes of pond to choose from.
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Unwanted invasive pond plants
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Some floating plants are invasive and not recommended as if added to your pond are very hard to get rid of. Floating pond plants to avoid are duckweed and fairy moss as they grow quickly and can completely block out light to the depths of the pond. We do not sell these.
These are the plants DEFRA list as 'to be avoided and composted with care if they are in your pond':
    
Azolla filiculoides Crassula helmsii Hydrocotyle ranunculoides Ludwigia grandiflora Myriophyllum aquaticum
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The Be plantwise campaign by Defra and the Scottish Government launched by Charlie Dimmock in February 2010 wants to raise gardeners awareness about the threat of invasive non native plants which can take over your pond and damage the environment if they become established in the wild |
The campaign has 3 messages:
1. Know what you grow: Key invasive pond plants to avoid are:
Parrots Feather (Myriophyllum aquaticum), Floating Pennywort (Hydrocotyle ranunculoides), Australian Stonecrop (Crassula helmsii), Water Primrose (Ludwigia grandiflora), Water Fern (Azolla filiculoides).
2.Compost with care: Don't dump aquatic plants in the wild - you could be breaking the Law. Always dispose of old plants and pond plant material reponsibly by composting or using a green waste bin. By composting excess pond plants carefully we can all help the environment and reduce clean up costs.
3. Stop the Spread: Be careful if you move pond plants around - even tiny fragments can lead to massive problems in time. Take care when maintaining your pond or disposing of waste water.
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