Making a clay lined pond

There's very little surface water on our allotments in St Ives so what better than to have a pond on my plot, thought I almost a year ago. Hopefully loads of wildlife to observe while taking a rest with a cup of tea.

Thought a lot about the benefits of rigid v sheet pond lining before it hit me... whenever I dig a hole in the winter it quickly fills with water and stays filled. Could the heavy clay hereabouts have something to do with it? Could I make a clay lined pond? It would certainly fulfill one of my ongoing allotment criteria... something for nothing.

So this post is all about my pond experience. If you live in an area of moderate or significant clay as indicate by the map below you might want to consider a clay lined pond. My hole was dug in November 2010 and the assumption about clay was immediately confirmed... the flipping' thing was full of water before I'd finished and most of the work was completed up to my wellies in wet. Since then the development has been amazing. The mucky hole in the ground has transformed into a pond of clear water, home to a thriving community of plants and wildlife, always a source of interest while taking a rest.

Besides having a pond for free I was also able to stock it gratis... a call on allotment chums brought in pond plants, mud to 'seed' the water with bugs and a bucket full of frog spawn. Added to that I'd raised perennials from seed collected in my garden and transferred excess plants, so the pond and surrounds were soon bursting with new life as Spring arrived.

Unfortunately also collected some unwanted blanket weed which needs periodic cleaning out, so do be careful you don't accidentally introduce unwanted residents if you decide to instal your own pond. This invader came from one of the allotment water tanks. And you do need to carefully consider how you'll maintain the water level in your pond during summer. At its hottest I'm wheelbarrowing in over 40 gallons of water week... that's a weight of 28st (181kg). So you need a water source nearby.

Below you'll find links to more details on the plants and wildlife in my pond as well as a photo record of development taken at two week intervals. This post will be updated periodically to form a record of the pond for 2011. If you're thinking of having a go yourself and have a question leave me a comment or use the 'Contact me' tab above and I'll get back to you quickly.

Here's the map of England showing areas of clay concentration. If you want to see a map for a different area search Google for a map showing clay deposits.

Here's a list of what's in my pond (this doesn't include the wildflowers and other plants surrounding the pond)...

Note: The first home produce frogspawn arrived in spring 2013. To view the post about the click Allotment Heaven: Frogspawn!.

And here's a series of images showing how the pond has progressed from the beginning.

Nov-2010: The pond dug to it's deepest at 1 metre (wellie depth) and the sides coated in clay, the whole site is mud,mud, mud. Didn't need to worry about how I'd fill it with water... as I dug it filled!

Mid Jan-2011: Widened the pond to include more shallow edging and create a small island.

End Jan-2011: Not much change... still lots of clay earth surrounding the pond that needs clearing.

Mid Feb-2011: Now managed to clear the excess earth and have the pond surrounds gently sloping inwards. Loads of earth moved away to other parts of the allotment though... what am I going to do with it?

End Feb-2011: Not much change... waiting for Spring so can do some planting.

Mid Mar-2011: Now things are starting to happen! Moved quite a few plants from the garden and found a home for Becky's unused rockery... creating a dry stone wall near the pond with all the excess earth banked up behind it. A call for help from fellow allotmenteers also resulted in free pond lilies, irises and oxygenating plants as well as pond mud to 'seed' the water with bugs.

End Mar-2011: Added another shallow edging area on far side of pond. Dry stone wall now finished and turfed along top. Gifted a bucket of frog spawn.

Mid Apr-2011: Added logs against far side of pond with a damp shelf underneath for frogs etc to hibernate in Winter. Seeded in front of dry stone wall with wild flowers. Seeded grass area to left.

End Apr-2011: Tadpoles have hatched into water that's now much clearer. A stoney area added to the right. Plants starting to establish themselves.

Mid May-2011: Water now clear... but with warmer weather having to add water weekly.

End May-2011: More plants added, mainly perennials grown from seed collected in the garden.

Mid Jun-2011: First froglets appeared at last!

End Jun-2011: Planted up the bank behind the dry stone wall with herbs, the wild flowers in front are now well established. The bench is moved to the pond whenever we take a break for a cup of tea and a view of what's happening... the first pond lily flower has appeared! Water not very clear 'cause I've just finished adding more.

Mid Jul-2011: Everything now well established and the froglets are striking forth all over the plot. The globe artichokes I planted a month ago are growing quickly on the left.

End Jul-2011: Lots of things flowering now, loads of wildlife in the pond and around. Damselflies and dragonflies being attracted by the water.

Mid Sep-2011: Oops... where did I put the August photos? Here's the pond now well established and always the source of interesting happenings.

End Sep-2011: Noticed a new inhabitant of the pond... a sedge plant growing to the left. Two larger frogs also appeared from under the log pile, maybe getting ready to hibernate in spite of the 85F temperatures.


  1. Brill sequence of photos! It is fab after less than a year, well done you.

  2. Very interesting. I like the way you documented what you did over time with pictures. This post obviously took a long time to complete.

  3. That's delightful!

    Here in Northern California they take a dim view of still water, because mosquitoes are a vector fo West Nile Virus. The local government will deliver mosquito fish (whatever that is) to your door. I understand that the local raccoons find these fish quite tasty.

  4. Thanks for the comments Bridget & Kathy. I've been storing the photos (other than those for August!) for some time... in fact I took four each fortnight, each from a different angle. Aiming to keep up the snaps and update the post periodically with more images and notes on the wildlife.

    Thanks, John

  5. Hi Lisa, Robb... we don't have such problems in our locale other than there's very little surface water about. I'm hoping I'll get some newts populating the pond some time in the next year. Regards, John

  6. Hello! We're considering doing a clay lined pond, we live in Oxfordshire and like you whenever I dig a hole it fills with water! Did you "puddle" the clay in layers to construct it, or did you just dig a big hole knowing that it would just fill up? Many thanks, Kathryn!

    1. Hi Kathryn... I did puddle the clay. There was no shortage of clay below the topsoil, but I ensured that was packed tight by giving it a good tread. Above the clay was a layer of topsoil. So I used some clay to create a clay band up to the water level. No use going higher than that since any clay in the open will dry, crack and leak. It's much more nature friendly to line with clay. You'll be amazed at the wildlife such a pond attracts. Even got newts the following year, was so exciting! John

  7. Peg Eleonore3:25 pm

    Hi Kathryn, as I am in the process of making a clay pond myself, I find your article very interesting. As I've been reading that the walls of a clay pond should be 30 degrees for the clay to 'sit', I wonder how that works for you? With a depth of a meter and two levels for the planting it would be 4 metres in size, I calculated, which is far too big for our allotment! Could you share the diameter of your pond? And, you mention it to be '1 metre deep = 1 wellie', is that correct? With 1 metre being 100 centimeters, I doubt (but being Dutch I can be wrong) that your wellies are that high :-). Hope to hear from you, kind regards, Peg Eleonore (Rotterdam, NL).

    1. Anonymous4:36 pm

      Hi Peg... I think I mentioned one metre since that's the recommended depth to avoid full icing up during severely cold weather. Only a small part of the pond was to that depth, the rest about wellie depth. Not sure about the 30 degrees. Mine did slope, and I had to periodically replaster the clay when it cracked near the water surface. To reassure you, ANY size of pond will benefit an allotment. Birds & bees will drink from it. Insect life will be multiplied. Frogs will certainly spawn. And it's a constant source of interest. Go for it! John

    2. Anonymous3:54 pm

      Thank you, John!


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