Make a garden pond

Freshwater Habitats Trust’s Dr Jeremy Biggs made another pond in his garden, following the guidlines of clean and shallow water, making a pond that will be great for wildlife.

Here Jeremy shows you step-by-step how to make a pond:

Step 1. Mark out the pond shape that you want
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You can use a length of rope, hosepipe, string between sticks, bamboo canes etc to mark out the pond shape before you start digging.

For wildlife, the pond shape is less important than the depth (you need lots of shallow water) and the how clean the water is, and what the edges are like.

So you can make a pond that is ‘natural or ‘formal’ and it just depends on what looks good in your garden.

Step 2. Remove the turves
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Start to dig out the turf but don’t dig down too deep. Keep the turves because you can use them round the edge of the pond to secure the liner, but don’t put the turves in the pond!

They will almost certainly add a massive blast of polluting nutrients to the water which will plague you for the rest of the pond’s life.

Step 3. How deep to dig?

It’s very easy to dig a wildlife pond too deep and end up with a miniature version of a giant open cast mine.

A wildlife pond should have lots of shallow water – roughly 50% shallows, and the deep area is not more than 30 cm.

The standard advice that you need to dig down to 50 cm or 60 cm or whatever the writer thinks applies only to fish ponds. The reason you’re told to do this is that the pond might freeze solid. This might be true in northern Canada, but is nonsense in the UK. The other reason – that oxygen may run out – is probably true sometimes but is not a cast iron rule.

If you read the Garden Ponds Blog, you will know that in my first shallow garden pond, oxygen levels rose during the ice cover this winter to double the normal value.

Avoid a cliff
The simple act of removing the turves can create a massive steep cliff right at the edge of the pond, where you want to get the gentlest slope.

You can raise the turf, remove roughly half the soil from each turf making it half the thickness, and place the spare soil in from the of the turf so making the slope from pond to grass a bit gentler. This might not be the ideal solution but it is fairly quick to do.

Step 4. Shallow water is key for wildlife
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Now the pond bottom will be at the same level as the bottom of the turf at the edge of the pond.

But the real way to get shallow water in a small pond is have shallow basins.

So this is the final shape: in large parts of the pond, it hardly looks as though there’s been any digging at all. This is the right depth for pond wildlife.

  • Tadpoles love shallows: it’s where they spend a lot of time in my first pond.
  • Almost all other pond wildlife is happiest in very shallow water as well.
  • Most garden ponds are too deep for their area: if you want a half metre deep pond, or deeper, it needs to be much bigger or you end up with very steep sides.

Step 5. Check the level
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It’s important to get the pond level otherwise some of the water will run out and you will have bare liner on one side. You’ll need a spirit level that you can put on a piece of wood that will go right across the pond. I didn’t have one at home so had to buy a piece from the local timber merchants for a fiver. I expect you could scrounge something like this for free.

Step 6. Add the liner
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Now the lining: it’s best if you can use underlay under the rubber liner.

You can buy the underlay if you don’t have any old carpet around. Simply put down a double thick layer of the underlay on sale at the garden centre.

Remove any stones carefully.

As the total bill for liner and underlay was £134, and as I will have hours of pleasure from the pond for nothing apart from this, I didn’t mind the expense. The liner itself was £90.30. But the resourceful could do it for less.

Step 7. Add the water
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If you are patient you can wait for the pond to fill with rainwater. or you can collect rainwater in your water butts and use this.

Notice – no hoses. Most tapwater is not fit to use in a pond because it’s full of nutrients. In some parts of the country (in the north, for example) its OK where it’s come off the moors. Down south, its mostly not fit to use in a pond.

From here on in we have a pond!

Step 8. Wildlife
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What’s next?

Well, I will add some plants to this pond: local, native, wild sourced plants (only collected from landowners who’ve given permission).

I won’t add ‘pond sludge’: the pond doesn’t need to be ’started’. I’ve started it simply by making the hole and filling it with clean water, and anyway that sludge is quite likely a source of nutrients from someone elses pond that I don’t need.

I don’t want soil, or turves or fish food or any other of the pollution sources that commonly find their way into ponds. We will have more than enough just coming down in the rain (rain itself is slightly polluted these days).

I will put some clean children’s play sand on the bottom to make the pond a little more natural looking. This is chemically inert so no pollution problems, provided it’s clean.

And the wildlife? Well that started to arrive on day 1 with little flies laying their eggs, and on day 2 the first water beetles flew in.

I wish you every success with your pond creation!

Need more advice?
If you have any questions that are not answered here then please contact us at info@freshwaterhabitats.org.uk