Revamping soggy area of garden

A question about : Revamping soggy area of garden

With the heavy clay soil here creating a drainage problem in an area of my garden I have decided to grow food in, it looks as if my best bet is:

- to have the top layer of soil and clay underneath it removed

- put in a layer for drainage (gravel? shale?)

- put back some new topsoil in a thick enough layer to grow my food in

So my questions are:

1. How deep does this new layer of topsoil on top of the drainage layer (of gravel? shale?) need to be in order to have sufficient depth to it to grow whatever fruit or vegetables I please? I am going to be growing things like grapevines, fruit bushes, etc, on this land and am unsure how much depth of soil these will need for their roots. Would 12 depth be enough?

2. What would be the best thing to use for the drainage layer? I'm rather picturing ordinary garden gravel, or do I need something else and, if so, what?

3. Is there anything else I need to take into account in order to be able to just use this bit of my garden exactly as I have decided?

Best answers:

• Simplest is probably a raised bed, if you dig down into clay soil it'll create a 'sump' which'll fill with water unless you lay in drains to actually carry the water away.
• I think we visited this matter before with another poster, and my answer remains the same, which is that you cannot drain an area without having a route for the water to get away.
  All you will do is make the water sink more quickly to the base of the layer you have excavated, and there it will sit, unless it has an escape route.
  The area mentioned hasn't been quantified, so it's difficult to be sure what action you might take, but if it's relatively compact, a partial answer might be to go upwards and construct raised beds. They at least could be made to drain, if above the level of surrounding garden.
• I've done some reading-up on the question of raised beds and I don't think its possible to raise the earth up at that point. It could be done one side of the area in question (ie because there is a wall to contain the earth).
  However, at the other side of this bit lies one of my garden paths and any raised earth would come noticeably higher than that level.
  The hard landscaping of my garden I intend to do at some point will be a "one fell swoop" thing of ripping out all existing paths/paving/etc and replacing with something rather nicer-looking and some re-arrangement of the garden and it won't be cheap.
  Hence, it wont be peanuts to alter this particular section of my garden (at a very quick guesstimate, without measuring, some 100 square feet or so and its width back to wall is about 5') - but way cheaper than the total garden revamp due at some point.
  Hence, my topsoil on that seems to be only about 3" in depth and then down to very heavy clay. Hence me planning on just getting a mini-digger in to scoop out down enough depth to just put down a "drainage" layer and then top up with a decent depth of topsoil in line with that garden path (NB: When I do that expensive rearrangement of garden in time to come I will still have a garden path at that point, because it's along one of the exterior walls of my house, so I have to have a path there).
  Its quite a narrow-ish stretch of land and has a land drain along by the wall leading off my plot, so I guess I'm okay for enough drainage between that and a "drainage" layer put down?
• If you can take a drainage layer directly to a land drain, then that would be good.
  I can't see any reason why a deep bed shouldn't run beside a path, mainly because mine always have! Of course a method of containment is needed, whether it's gravel boards, a concrete block or brick wall, railway sleepers, or whatever. The cheapest, which I've done here, is half round horse rails screwed or nailed to 3" square uprights. Looks better than it sounds.
  I think you'll need more than 12" of soil if it's directly above gravel. Personally, I'd go for 16"- 18", but grapes won't mind if it's shallower than that.
• Well, I guess that's a Plan B sorted then in worst case analysis set-up (ie Plan A doesn't work or costs so much that I'm wincing too heavily to write out a cheque for it).
  Plan C (ie worst case analysis plan) is to think in terms of things like a gunnera manicata plant for instance and an aronia berries plant (as these both like swampy conditions but have an edibility factor).
  One way to look at it is at least a huge type gunnera plant would pretty rapidly make this house/garden look less "conventional" than they currently do and that's a plus in my book, as both house and garden currently look way more conventional than I am personally from the outside and I'm wincing at that...(anyone would think I'm a little old pensioner looking at them outside at the moment....well...I may be little and I may be on a (half) pension but that image is so far from reality that a bit of "shift the picture" would help).
  Crosses fingers and hopes to goodness that gunnera M-- isn't going to become one of those things "everyone and their spouse and dog" has and looking thoroughly conventional by the end of it...as I do like gardens being a bit "wild" and "personal" (part of why I go for permaculture LOL).
• The other really important thing to work out is "where is this water coming from?"
  It may be that renovating a ditch higher up the hill will remove all the water before it affects this area? Or that you can divert the water as it arrives on your land?
  Or is this coming off a roof?
• Part of the source of the problem is "Its Wales you know...and rain is one thing there is plenty of here"
  The drainage that should be there in the hard landscaping is currently missing (no...I don't know why either...considering the house has had several previous owners before me and you would have thought one of them would have dealt with it).
  That is part of the expensive hard landscaping work I will be doing when I have the money for it...ie making sure rain that lands on paths/etc around the house has drains to go down okay, rather than running into my earth.
  The other aspect of the problem though is what the earth itself is like....ie that clay, with downright hard clay not very far at all beneath the surface.
  I have noticed that a lot of gardens in my immediate vicinity have "loads" of hard landscaping, rather than being proper "garden" set-up and am guessing that the clay soil is part of it and possibly another part of it is the Japanese Knotweed that I never even came across before I moved here...but have learnt to recognise a mile off since coming here. Hence part of the reason for lots of cheapie/bog-standard boring paving in many gardens round here I guess, rather than something "nice" and "garden-like".
  I'm sticking to its going to have to be "nice" and "garden-like" personally...hence a very sorry-looking bank account making it be what I personally recognise as being a garden.
  The water coming off the roof of my own house is (should be!) getting caught in my waterbutts, but the thing is there is still one heck of a lot of rain going on here that needs somewhere to go at present.
  The neighbourhood norm of cheap paving stones/gravel/tarmac for the "high priority here parking of cars"/soggy mossy grass is not an option for me personally, as I'm quite homesick enough without the proper garden that is part of what I moved for. Hauls out chequebook again/examines bank statement/sighs and gets on with it.... That's the thing for me personally....it has GOT to be a "Home Area" style garden....
• There's no shortcuts when dealing with clay soil in an area of high rainfall, just get digging and lay in the field drains...
• Hi,
  Have read the forums for a while, only posting here because we had a similar issue when I was a child. The day we had moved into our house the garden was literally a lake, but after some pits were dug, the water drained back into the earth.
  My mum (with help of friends) dug three deep pits in the garden, about 4ft-5ft wide and about 5ft-6ft deep, they dug until past the clay layer, then the pits were filled with hard core. By breaking through the clay layer, the water was able drain away.
  I remember that they also built up the height of the garden a bit too with topsoil by a couple of inches, before laying new lawn. The number of pits depends on the size of your garden. Ours was about 25ft x 50ft (I think).
• I think the heavy use of hard landscaping in West Wales is more down to tradition, since it was even more prevalent in my relatives' area than yours, and they had no great problem with clay.
  As Magic Cat says, a hard pan beneath clay can sometimes be broken through, but it depends how deep the clay goes. I've had a couple of 8' deep pits dug recently in my field, looking for a rock seam, and in one, the clay layer bottomed-out into rock at around 7'. Good luck if it's like that!
  There's two ways to look at an area of difficult garden. One is to throw money at it, and the other is to concentrate scarce energy and Ј on areas which are more productive, making them even more so. I wouldn't necessarily abandon your wet area, but I'd get on with the rest first.
• You could plant water loving vegetation (https://www.rhs.org.uk/advice/profile?pid=303)
  This may help a little.
  Just watch out for slugs........
• That was one of my thoughts, ie re planting water-loving vegetation - but research revealed just how few edible water-loving plants there seem to be and I'm determined my garden is all going to grow food. Slam into a brick wall time then.....
  So, I've duly had a quote through to "put matters right" there and its a bit eye-watering, but I cant really see any other way, as the area concerned represents about half my growing space in this garden. I could ignore an area that size if I had a big garden, but with a very standard-size one that isn't an option without severely restricting how much food I can grow.
  Working on a "cost per wear" basis in effect (ie the one used to determine whether clothes represent good value for money), I would say that estimate I have received comes to somewhere between Ј100-Ј150 per year of estimated usage I expect to get from that garden. So, put like that, I should get my money back and more..iyswim.
• I was quoted Ј10,000 to makeover my garden. DIY exc. laying the new turf it was more like Ј1,750
• Regarding the digging up of existing topsoil (aka The Swamp) and heavy clay layer underneath - when would be a suitable time of year to do this?
  I'm imagining that maybe it will now be necessary to wait until the spring to do this when, hopefully, The Swamp will have dried-up a bit??
  Should think it will be easier to dig up dry topsoil, rather than swampy topsoil?
  Also, buying in new topsoil at this time of year (by weight) would probably mean that part of that weight I was paying for would be water that it was waterlogged with (ie rather than topsoil itself) iyswim?
• I did mine at Easter, then you get the benefit of a full season in the replanted garden.
  You need 8yd skips for the spoil, no point in faffing about. I'd also consider hiring a mini excavator,rather than digging with a spade, but that depends on access.
  Top soil should come in 1 tonne bags, but I recommend selecting bags in the builder's yard as the percentage of sand can be variable.
• Ј150 buys a lot of vegetables!
  Personally, I would not go for removing much, only what would be required to insert a French drain leading to the land drain, assuming that's working. Then I would put more on top to raise the level above the path, leaving room for another drain/gulley at the side of the path so it's not flooded.
  I would retain the extra soil with railway sleepers or something similar that would allow water through. Walls are expensive. Assuming you have a bit of top soil already, you only need to go up about a foot.
  Yes, driving a digger over your garden at this time of year isn't recommended, and anyway, there's no need.
  Topsoil comes in varying qualities. Ask to see exactly what you'll be getting and inspect it before they dump it. Some suppliers will try to pull a fast one, as they did at the school where I worked, leaving me to sort it out. They are less likely to do this if they are reputable, and if you look as if you know what you're doing!
• There seem to be levels and levels of topsoil from what I can see. I've been told that the topsoil I've bought in previously was too fine (as I recall) and I need some with a bit of "grit??" in it to allow for drainage.
  What would you be looking out for topsoil-wise Dave?
• Yes, a bit of grit is useful in soils which don't contain it, but the main thing is to avoid too much clay. I'd guess your better imported soil might come from Pembrokeshire, but there are sand & gravel pits not far from you too, so there's obviously localised soil which isn't all stodgy clay.
  A certain level of clay is OK for many purposes, but probably not if you already have plenty. Lots of clay in the soil near me, say in Crediton, but it's still good for arable crops.
  I used to buy all my top soil from a place on top of the Mendips which produced bagged composts for the trade, so I was spoiled. That meant I could buy it weed free too, if I wanted, and I bought grit separately and mixed it as I went along according to purpose. But I had a trailer, and as much of the cost is in transport, I avoided all that.