Building a "wildlife pond"
Discussion
I've decided I'd like to build a pond in my back garden. I've never owned or built a pond before, although I do have previous experience with freshwater aquaria so I do have a decent understanding of the way aquatic systems work (nitrogen cycle etc). I thought I'd describe roughly what I've got in mind, and perhaps people can tell me where I've got things wrong!
Firstly, a picture of the location:
The location is in a sunny spot, and not overhung by any trees - although there are large mature deciduous trees in neighbouring gardens, so leaves will always be a slight issue. There used to be a large dead willow tree there about 5 years ago, so there are the rotting remains of the stump - this should make it easy to hack through any roots that I find when digging.
The tall clump of grass will stay, but the cat will have to move! (Although she's useful in the picture for scale...) As you can see, I've laid out a hosepipe in the rough shape I'm considering, although I've stretched it out slightly further on the left-hand side since I took the picture. I think it's about 3m long and not quite 2m wide.
My plan is for a "wildlife" pond, with plenty of plants to encourage insects, amphibians etc. Am I right in thinking that fish should not be part of the picture? I'd like a couple of goldfish in there, but would they eat all the other creatures that I'm interested in, and/or their eggs, larvae etc?
I'll be going for a flexible liner. I think I've read that butyl is best and lasts longest, albeit expensive. Is that correct?
I want to reach a depth of about 2 feet in the middle, with "shelves" at about 12" and 6" with various plants. I have a vague idea to make the right-hand end shallower - perhaps only 3" or 4" and grow bog plants in that area.
I'd like to bring the lawn right up to the edge, rather than have rocks or any paving around the edge. My plan is to embed some kind of flexible barrier around the edge, to about the level of the lawn soil or perhaps a fraction higher. The pond liner would loop up over this, with the intention that no water would be able to run off from the lawn and pollute the pond with excessive nutrients. A further 6" or so of liner would then be buried at an angle underneath the turf - I'd lift the turf to bury it and then replace. Does this sound like a plan that will work?
There will, of course, have to be an area where the edge allows creatures to crawl in and out of the pond. I plan that the rear edge (near the tall grasses) will provide this, perhaps with some pebbles or shingle in that area.
I want water movement, so I plan to have a low voltage pump driven by power from my greenhouse about 8 metres away, and bury the cable under the lawn. I think I'll put the pump at the bottom of the deepest part, and have the water return via a hose into the shallowest part. My thinking is that this will help with oxygen distribution, and keep temperatures down in the shallow end. It'll be quite gentle, but hopefully enough to make a slight "babbling" sound. Will the water movement result in excessive evaporation?
What plants should I have? I'd like to have a small water lily if possible - should that go in the deepest bit? Should I plant all my plants into baskets rather than direct into a substrate? For that matter, what substrate (if any) should I have in the pond? Is ordinary garden soil suitable for planting (my soil is fairly heavy)? What marginal plants do you recommend?
Filling the pond: Ideally I'd prefer to use rainwater, but I think the quantity will be far more than I can provide. I'm guessing it'll be between 1 and 2 cubic metres, so far more than my water butt can provide. Is it okay to fill with tap water, or will that charge the pond with too much nitrate/phosphate? Should I use a tapwater conditioner (e.g. Aquasafe)? Do I need to measure how much water goes in? I could do that by timing how long it takes to fill and compare with how long it takes to fill a bucket.
And finally, do I need to do anything to help wildlife to find the pond? The location isn't perfect, because it's a bit isolated in the middle of my lawn. So will I need to put frog spawn in there or will they find it? I did find a newt in my greenhouse a few nights ago, so they're in the vicinity!
Any help, suggestions, warnings, etc very gratefully received!
Firstly, a picture of the location:
The location is in a sunny spot, and not overhung by any trees - although there are large mature deciduous trees in neighbouring gardens, so leaves will always be a slight issue. There used to be a large dead willow tree there about 5 years ago, so there are the rotting remains of the stump - this should make it easy to hack through any roots that I find when digging.
The tall clump of grass will stay, but the cat will have to move! (Although she's useful in the picture for scale...) As you can see, I've laid out a hosepipe in the rough shape I'm considering, although I've stretched it out slightly further on the left-hand side since I took the picture. I think it's about 3m long and not quite 2m wide.
My plan is for a "wildlife" pond, with plenty of plants to encourage insects, amphibians etc. Am I right in thinking that fish should not be part of the picture? I'd like a couple of goldfish in there, but would they eat all the other creatures that I'm interested in, and/or their eggs, larvae etc?
I'll be going for a flexible liner. I think I've read that butyl is best and lasts longest, albeit expensive. Is that correct?
I want to reach a depth of about 2 feet in the middle, with "shelves" at about 12" and 6" with various plants. I have a vague idea to make the right-hand end shallower - perhaps only 3" or 4" and grow bog plants in that area.
I'd like to bring the lawn right up to the edge, rather than have rocks or any paving around the edge. My plan is to embed some kind of flexible barrier around the edge, to about the level of the lawn soil or perhaps a fraction higher. The pond liner would loop up over this, with the intention that no water would be able to run off from the lawn and pollute the pond with excessive nutrients. A further 6" or so of liner would then be buried at an angle underneath the turf - I'd lift the turf to bury it and then replace. Does this sound like a plan that will work?
There will, of course, have to be an area where the edge allows creatures to crawl in and out of the pond. I plan that the rear edge (near the tall grasses) will provide this, perhaps with some pebbles or shingle in that area.
I want water movement, so I plan to have a low voltage pump driven by power from my greenhouse about 8 metres away, and bury the cable under the lawn. I think I'll put the pump at the bottom of the deepest part, and have the water return via a hose into the shallowest part. My thinking is that this will help with oxygen distribution, and keep temperatures down in the shallow end. It'll be quite gentle, but hopefully enough to make a slight "babbling" sound. Will the water movement result in excessive evaporation?
What plants should I have? I'd like to have a small water lily if possible - should that go in the deepest bit? Should I plant all my plants into baskets rather than direct into a substrate? For that matter, what substrate (if any) should I have in the pond? Is ordinary garden soil suitable for planting (my soil is fairly heavy)? What marginal plants do you recommend?
Filling the pond: Ideally I'd prefer to use rainwater, but I think the quantity will be far more than I can provide. I'm guessing it'll be between 1 and 2 cubic metres, so far more than my water butt can provide. Is it okay to fill with tap water, or will that charge the pond with too much nitrate/phosphate? Should I use a tapwater conditioner (e.g. Aquasafe)? Do I need to measure how much water goes in? I could do that by timing how long it takes to fill and compare with how long it takes to fill a bucket.
And finally, do I need to do anything to help wildlife to find the pond? The location isn't perfect, because it's a bit isolated in the middle of my lawn. So will I need to put frog spawn in there or will they find it? I did find a newt in my greenhouse a few nights ago, so they're in the vicinity!
Any help, suggestions, warnings, etc very gratefully received!
I've started!
So far I've excavated most of it down to about 12", except for the right-hand end which is only 8". There will be a deep bit in the middle, down to about 30" if possible.
Annoyingly, this picture fails to show the depth I've dug down to...
For the shallow section, I plan to have 2" or 3" of soil substrate, and the water will be a couple of inches over that. There will be a retaining ridge (still below water) to keep the soil from spreading to the rest of the pond. I might try to bank it up towards an edge. My aim is to grow bog plants in this area.
Should I use special aquatic soil, or will my garden soil do?
I'm quite tempted to keep a few sticklebacks in there, but I'll definitely wait until the pond is at least a couple of months old.
Edited to add: I feel very lucky that my topsoil goes down nice and deep. There's no sign of any change to poorer subsoil yet. I've redistributed the topsoil to beds around the garden.
Edited again: As expected, I've encountered a lot of rotting willow roots, but they've been soft enough not to offer much resistance. Any large chunks of rotting wood I've stacked up in a corner of the garden, and carefully moved lots of stag beetle larvae as I've found them. Hopefully I'll have a new stag beetle nursery!
So far I've excavated most of it down to about 12", except for the right-hand end which is only 8". There will be a deep bit in the middle, down to about 30" if possible.
Annoyingly, this picture fails to show the depth I've dug down to...
For the shallow section, I plan to have 2" or 3" of soil substrate, and the water will be a couple of inches over that. There will be a retaining ridge (still below water) to keep the soil from spreading to the rest of the pond. I might try to bank it up towards an edge. My aim is to grow bog plants in this area.
Should I use special aquatic soil, or will my garden soil do?
I'm quite tempted to keep a few sticklebacks in there, but I'll definitely wait until the pond is at least a couple of months old.
Edited to add: I feel very lucky that my topsoil goes down nice and deep. There's no sign of any change to poorer subsoil yet. I've redistributed the topsoil to beds around the garden.
Edited again: As expected, I've encountered a lot of rotting willow roots, but they've been soft enough not to offer much resistance. Any large chunks of rotting wood I've stacked up in a corner of the garden, and carefully moved lots of stag beetle larvae as I've found them. Hopefully I'll have a new stag beetle nursery!
Edited by Dr Mike Oxgreen on Saturday 5th July 17:33
Started digging the deep section, and almost immediately encountered something mysterious that threatened the whole project:
It's a ceramic material, in sections about 12" long and not really joined together - I could move a section with my foot.
It's times like these that having an amateur archaeologist as a father-in-law is rather handy. A quick call to him, and he didn't even look at the picture before telling me what it is: a land drain. Probably put in 100 years or more ago, when this land was farmland - which also explains why my topsoil is so deep (you can see that I'm only just reaching the subsoil now at about 18" depth).
So according to my f-in-law it's perfectly safe to rip it out and isn't likely to cause any problems.
Onwards and downwards!
It's a ceramic material, in sections about 12" long and not really joined together - I could move a section with my foot.
It's times like these that having an amateur archaeologist as a father-in-law is rather handy. A quick call to him, and he didn't even look at the picture before telling me what it is: a land drain. Probably put in 100 years or more ago, when this land was farmland - which also explains why my topsoil is so deep (you can see that I'm only just reaching the subsoil now at about 18" depth).
So according to my f-in-law it's perfectly safe to rip it out and isn't likely to cause any problems.
Onwards and downwards!
Edited by Dr Mike Oxgreen on Sunday 6th July 10:58
The deep section is now dug down to about 30", although I've left a section at about 20" in addition to a shelf at 12" on one side and about 5" on the other side.
f
k me, the heavy, sticky clay subsoil was a nightmare to dig through!
This picture shows that there's also a new bed nearby, to be planted with shrubs - should provide a bit of cover for wildlife transiting to/from the pond.
f
k me, the heavy, sticky clay subsoil was a nightmare to dig through!This picture shows that there's also a new bed nearby, to be planted with shrubs - should provide a bit of cover for wildlife transiting to/from the pond.
Built the retaining ridge yesterday, which will prevent soil from the shallow bog section from migrating into the rest of the pond. Dug a small channel and filled it with mortar so that the ridge is keyed into the soil below, then heaped the mortar up using a trowel. Finally, I made some slightly sloppier mortar and "buttered" the woven backing of a piece of old carpet, then stuck it on top of the ridge to protect the liner from the mortar. Quite pleased with how firmly the carpet has stuck:
Today I'm hoping to get the lawn edging done, and if time allows I'll actually get the liner in!
The deepest section of the pond keeps filling up with water, but I've discovered there's little point in bailing it out because it just fills up again over a period of a few hours. I'll simply have to bail it out just before I fit the liner, then get water into the liner as quickly as possible to counteract the seepage of water from the surrounding clay.
Edited to add: Just realised it might seem a bit back-to-front talking about doing the edging before the liner goes in. What I meant was that I'm inserting the spade under the turf and cutting into sections that can be lifted individually. Doing this requires me to stand inside the pond - hence doing it before the liner.
Today I'm hoping to get the lawn edging done, and if time allows I'll actually get the liner in!
The deepest section of the pond keeps filling up with water, but I've discovered there's little point in bailing it out because it just fills up again over a period of a few hours. I'll simply have to bail it out just before I fit the liner, then get water into the liner as quickly as possible to counteract the seepage of water from the surrounding clay.
Edited to add: Just realised it might seem a bit back-to-front talking about doing the edging before the liner goes in. What I meant was that I'm inserting the spade under the turf and cutting into sections that can be lifted individually. Doing this requires me to stand inside the pond - hence doing it before the liner.
Edited by Dr Mike Oxgreen on Saturday 12th July 09:43
And the liner is in, and it's full!
I reckon it took about 1,000 litres, based on the filling time. Just got to trim the liner and tuck the edges under the turf, which is today's job. I have a feeling that won't be as easy as I'm imagining. I'll probably cut the excess liner into "fingers" before tucking it under the turf, so that the grass roots can root around and through it - otherwise I imagine the grass around the pond will always appear weak and feeble.
Slightly cross with myself for damaging a large rectangle of the lawn. I unrolled the liner and left it spread out for slightly too long, and the grass got very warm underneath and wilted badly. So, top tip: a black liner on a sunny day will get hot very quickly! I put the sprinkler on straight away, so hopefully the grass will recover soon. In the picture, the excess liner is propped up on flower pots to stop this happening again.
The floating stuff came from the soil I put at the shallow end. I realised too late what I should have done: soak bucketsful of soil and strain off the floating material before adding to the pond.
I reckon it took about 1,000 litres, based on the filling time. Just got to trim the liner and tuck the edges under the turf, which is today's job. I have a feeling that won't be as easy as I'm imagining. I'll probably cut the excess liner into "fingers" before tucking it under the turf, so that the grass roots can root around and through it - otherwise I imagine the grass around the pond will always appear weak and feeble.
Slightly cross with myself for damaging a large rectangle of the lawn. I unrolled the liner and left it spread out for slightly too long, and the grass got very warm underneath and wilted badly. So, top tip: a black liner on a sunny day will get hot very quickly! I put the sprinkler on straight away, so hopefully the grass will recover soon. In the picture, the excess liner is propped up on flower pots to stop this happening again.
The floating stuff came from the soil I put at the shallow end. I realised too late what I should have done: soak bucketsful of soil and strain off the floating material before adding to the pond.
Edited by Dr Mike Oxgreen on Sunday 13th July 07:33
And the edging mostly done (except the bit in the middle - I'm planning on getting some stones to hide that bit). Reasonably pleased with how the edging meets the lawn - it'll look better once the lawn has grown into it a bit.
We've also bought a handful of plants to get it started - though obviously we need many more!
The yellow hose is just a temporary outflow from the pump. I intend to pile up some pebbles at one end of the shallow section (far end) and have the outflow bubbling up through the pebbles. I need to make an extension cable too - I'm not paying Hozelock £20 for their official one!
Pleasingly, within minutes of putting the plants in a bright blue damselfly came in and settled on one of the flowers.
How long before the water goes bright green?
We've also bought a handful of plants to get it started - though obviously we need many more!
The yellow hose is just a temporary outflow from the pump. I intend to pile up some pebbles at one end of the shallow section (far end) and have the outflow bubbling up through the pebbles. I need to make an extension cable too - I'm not paying Hozelock £20 for their official one!
Pleasingly, within minutes of putting the plants in a bright blue damselfly came in and settled on one of the flowers.
How long before the water goes bright green?
Edited by Dr Mike Oxgreen on Sunday 13th July 15:16
Edited by Dr Mike Oxgreen on Sunday 13th July 15:17
"If you build it, they will come."
It's not just advice given to the wives of architecture fetishists, it applies to ponds too!
My pond has only had water in it for just over a week, and already we have pond skaters, water boatmen; we've been visited briefly by damselflies and a dragonfly the size of a 737.
And, at the risk of sounding like Rolf Harris, there's this little fella...
He's just a common frog. We tried to get Waitrose frogs, but they were out of stock.
It's not just advice given to the wives of architecture fetishists, it applies to ponds too!
My pond has only had water in it for just over a week, and already we have pond skaters, water boatmen; we've been visited briefly by damselflies and a dragonfly the size of a 737.
And, at the risk of sounding like Rolf Harris, there's this little fella...
He's just a common frog. We tried to get Waitrose frogs, but they were out of stock.
Mr GrimNasty said:
Schoolboy error, you can't put non-native varieties in a wildlife pond, that's completely against the rules!
It's a funny year (or two), my lilies have already started shutting down for winter, bearing in mind some of them kept struggling on the whole way through last winter.
Yep, sorry - I'm not being anal about sticking to native plants! I've got one called "Justicia americana" with pretty orchid-like flowers which I suspect isn't native either. It's a funny year (or two), my lilies have already started shutting down for winter, bearing in mind some of them kept struggling on the whole way through last winter.
My lily has been losing its largest leaves and growing new, tiny ones just a couple of inches across. I read somewhere that this might be normal at this time of year, though I agree it does seem a bit early for it to be shutting down. I'll push a fertiliser tablet into its basket in the spring.
On the subject of plants, I've discovered a really good pond plant nursery on my way home from work, which sells every imaginable pond plant and is a great place to browse (they're open to visitors Wed to Sat).
Woody: that's not a pond, that's a lake! Must be wonderful in the height of summer.
The pond has had water in it for less than two months, and I snapped some kind of nymph sitting on a leaf stalk. Dragonfly I think - looks too stocky to be a damselfly. It was only about 5 mm long, so this picture is highly enlarged...
Fascinating facts about dragonfly nymphs: they breathe using gills inside their rectum, and can propel themselves by squirting water out of their anus.
Fascinating facts about dragonfly nymphs: they breathe using gills inside their rectum, and can propel themselves by squirting water out of their anus.
Edited by Dr Mike Oxgreen on Monday 8th September 18:38
Awesome picture!
We get quite a few slender pinkish-red dragonflies a couple of inches long - common darters, I think. Never managed to get a picture of one; they seem to have such good eyesight and always take flight before you can get close enough. We did see two of those flying in tandem just above the water and doing a "dipping" motion a few weeks ago, so maybe this nymph is the result of the eggs they were laying.
We get quite a few slender pinkish-red dragonflies a couple of inches long - common darters, I think. Never managed to get a picture of one; they seem to have such good eyesight and always take flight before you can get close enough. We did see two of those flying in tandem just above the water and doing a "dipping" motion a few weeks ago, so maybe this nymph is the result of the eggs they were laying.
I'm a novice gardener really! We've created a lot more depth in the borders by cutting out a more curvy, interesting shape from the lawn. The borders contain stuff like photinias, buddleias, rudbeckia, sedums, crocosmia... Here's an overview - lawn looks a bit ropey as it's still recovering from aggressive scarification:
Ironically you can't see the pond in that picture - it's obscured by the ceanothus hedge on the left hand side.
And here's a more recent pic of the pond. Quite pleased that the grass has tumbled over the edge - looks a lot more natural:
Ironically you can't see the pond in that picture - it's obscured by the ceanothus hedge on the left hand side.
And here's a more recent pic of the pond. Quite pleased that the grass has tumbled over the edge - looks a lot more natural:
Aaaarrgh! A problem!!
For some unknown reason, over the last 48 hours or so, the water has clarified dramatically. I can now see almost down to the very bottom of the pond, which is great.
But I can now see that a bullet-shaped rhizome from the tall ornamental grass next to the pond has pushed itself through the liner about 8 inches below he water line. Bugger! I should have thought of this, but I underestimated the power of nature!
So far, it doesn't seem to be causing an actual leak, as the water level stays fairly steady unless we get some hot, dry windy days. But I think something needs to be done to repair the damage and hopefully prevent it happening again.
Here's what I propose to do - any comments appreciated:
Picture:
For some unknown reason, over the last 48 hours or so, the water has clarified dramatically. I can now see almost down to the very bottom of the pond, which is great.
But I can now see that a bullet-shaped rhizome from the tall ornamental grass next to the pond has pushed itself through the liner about 8 inches below he water line. Bugger! I should have thought of this, but I underestimated the power of nature!
So far, it doesn't seem to be causing an actual leak, as the water level stays fairly steady unless we get some hot, dry windy days. But I think something needs to be done to repair the damage and hopefully prevent it happening again.
Here's what I propose to do - any comments appreciated:
- Cut down the ornamental grass (it dies back for winter anyway) so that the pond can be reached from that side.
- Pump water out of the pond into a water butt for safe-keeping, until the level is below the problem.
- Cut off the rhizome, and repair the hole by gluing a circular piece of liner over it and silicone around the edge.
- If possible, pull back the liner and insert a sheet of semi-rigid plastic behind it along the edge where he ornamental grass grows, to act as a barrier to stop further rhizomes coming through. Will visit "Hobbycraft" to see what materials they've got.
- Refill using the saved water and rain water, only topping up with tap water if absolutely necessary.
Picture:
Edited by Dr Mike Oxgreen on Thursday 11th September 07:52
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