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The Disaster of Double Digging Doom!!!


By peter


This is a request for help and yet another confession of gardening incompetence.

Last year I double dug a small patch of my garden and removed a lot of rubble. This involved days of hard labour and, in hindsight, some staggeringly poor judgement. I was so intent on getting nice, pure soil that I’ve managed to create a bog!!

All year, the double dug patch has been susceptible to water logging and moss. The cabbages that were planted in it only became healthy when I moved them to another spot. I’ve not planted anything in it since and it has basically been a disaster. You can see the size of the patch I dug in my blog from last year.

The border of the double dug area is level with the plant pot In the picture below (taken in June, double dug to the left). The cabbages to the right were originally smaller than those on the left but recovered and over took them once I’d moved them out of the ‘double-dug division of doom’.

Double dug on the left

As I’ve harvested the tomatoes this weekend, it’s only now I’m digging the soil again that I really appreciate the value of Wyeboy’s warning at the time about not removing too much grit with my seive. At about a spade’s depth the soil becomes something like a mix between quick sand and cement – what should I do?

I know (I think) that that the answer is to put a lot of stone back in the soil and dig it in. Slightly infuriating after taking a tonne of the stuff out last year:o)

I suppose my questions are these…
What sized stone should I add?
What type of stone should I add? – We have a bag of white border stone left over from the wedding table flowers, is that impractical or just extravagant in the extreme?
How much stone should I add?
Should I only dig stone into the second layer of soil (below the top soil)?
Would I be better off trying to mix the soil from the neighbouring areas in with the section I double dug?

Also, I was wondering; while I’m moving all this earth, is there anything else I might want to add while I’m down there? Maybe the seive I ridiculously used to create this mess in the first place :o)

Thanks in advance for your help.

The digging

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If such a soil situation was a problem in my garden I would be mixing small stones and large gravel into all of that boggy part.....or buying plants which like a bog garden. Lol.

I would save the white border stone for elsewhere.

Others with more expertise will no doubt advise.

Incidentally, we still need an entrant for the GoY Wellie Olympics 100 metres double-digging race.
Peter - it seems you've had more training for that event than ANYONE ELSE ON THE PLANET. (except maybe Andrewr)
You could be selected... :o)

5 Oct, 2008


Sounds like fixing the problem could certainly give me enough training :o)

5 Oct, 2008


Hi Peter. Horticultural grit and also plenty of organic matter such as composted stable manure, should do the trick.

Good Luck!

5 Oct, 2008


Okay Peter ~
I'll come back and check on your Olympic potential when the task is completed. :o)

5 Oct, 2008


To follow on from Claires advice Peter and given how much double digging you already done Id be tempted to raise the height of this border. Edged with gravel boards you could add grit and topsoil without having to dig soil out and return again.

5 Oct, 2008


Hello Peter: Do you know what lies beneath? Is your garden patch on the edge of your patio? Is your house new construction? I don't know if you'd care to try this...but ...could you take a core sample of the area underneath the bog? you may find that the poor drainage is caused by what is beneath your double digging. My guess would be clay or compacted gravel. A compactor may have been run over the area before the patio was put in. I found that developers put in heavy garbage fill and place 2 to 4 inches of "topsoil" over that and plant lawn grass because it's shallow rooted!!! A hardworking, double digging gardener comes along and all they reap is problems! best suggestion? raised beds? Check out Steve's pics.
don't give up...anybody who has the pluck to double dig will be a success eventually!!

5 Oct, 2008


Here we would add peat and mulch but have never heard of adding stone unless it was at the bottom of a bed for drainage pehaps...

6 Oct, 2008


Why not accept that you have a bog garden and plant irises and other plants that like their roots in the wet? Then you can grow your veggies in other areas whilst appreciating your pretty colourful bog garden.

6 Oct, 2008


Hi everyone, thanks for the advice :o)
I was a bit overexcited yesterday when I claimed it was a bog, it felt like one when I was digging but it only becomes very wet (water logged) at about a spades depth. I'm afraid a proper bog garden wouldn't work.

I've added a picture of the hole I dug yesterday.

Bonkers - I'malready half there with the double digging :o)
Lori - Our house is about 6 years old, so pretty new. I have unearthed a LOT of rubble from this little strip. A mix of builders rubble and the natural flint stone. When I double dung the small section I remember the bottom being pretty rocky, but I'm not sure what type of rock.

Raised beds sound interesting but the soil either side of the double dug patch seems OK, so I'd prefer to get this bit 'fixed'.

Horticultural grit sounds like the best bet.

6 Oct, 2008


Peter ~
Sorry, I can't resist ~
Double DUNG ?
Not sure that will cure the drainage problems.
Have you spent too much time looking at my photo of Cow Watering Lane ? :o)

6 Oct, 2008


Gardening certainly presents us with some challenges Peter. Here in Bristol we have thick heavy clay. We decided to go for pots and containers so that we had more control over the plants and their growing conditions. It looks from your photos that your soil is pretty heavy as well.Grit sounds like the answer to improve drainage.

6 Oct, 2008


Believe it or not...clay is the richest most nutritious soil..but it lacks an essential for root growth...air...Catfinch mentioned using peat and I agree.(I do realize that there is a movement afoot over your way to cease depleting peat's just the fastest way to use organics)..along with some builder's sharp sand.(it's much finer and lighter than grit)..mix that well with your clay and add some compost and you'll have a pretty good soil!
your soil is mostly need to add the other two components...organics and air...the sand is porous and well draining and helps air and water percolate through the soil.
If you have the opportunity to do so, I would suggest a perusal of a good book on soils...or check out will come away with a new appreciation of the complexity of basic good old dirt!! If you plan to continue to work in the same spot make sure you find out what is immediately below the bed...if it is a thick bed of clay you will save yourself some frustration and the long process of turning sub-soil into garden soil...I speak from experience. Good Luck!

6 Oct, 2008


Hi Peter. We have just moved back into an area with heavy clay soil, after several years away from this. I'll be turning the soil over soon, leaving the frosts to break up the large chunks then, in Spring, mixing in the old compost from compost from this year's pots, troughs, etc, as well as sharp sand (as Lori suggests above). I've never double-dug b4, I just keep adding compost. Also, I do prefer raised beds where I can have them. Good luck!

6 Oct, 2008


TT - Double dunging is the future!
Lori - Thanks for the advice, and for your blog :o)
Grenville - yup, I think drainage is the big issue.
David - Sounds like you've got a lot of work ahead, I hope your move went smoothly.

I don't think my soil is very clayey, the photo makes it look a look more grey than it actually is, the rest of the garden also seems fine, it's just the patch I removed a lot of stone from.

I'll check out what's at the next level underneath before doing anything, and try out Lori's experiment in a jar.

7 Oct, 2008


I think you were OK to have double dug - just don't do it again !! Just keep adding mulch, old spent compost etc on top and forking it in. It may take time but it will sort itself out. If it is heavy soil Dig it up into big chunks and let the frost break it up. I would try raising the bed a bit too - a small stone or brick wall and then just pile loads of compost or mulch onto it. Then plant through it.

I used to double dig but now I just lightly dig over the top and pile on the mulch and let the worms do their stuff.

7 Oct, 2008


Thanks Juid - at least it sounds like I'm sorting it out at the right time for frosts.

8 Oct, 2008


Hi Peter - I know I'm a bit late on this, but personally I wouldn't be adding stones back into the soil. The usual panacea for either poorly drained soil or soil that is too freely drained, is to add organic matter, which opens up heavy soil thereby allowing freer drainage. It would also provide the good stuff your veggies need to grow big and strong. I think it's interesting that you have permanent water in there - this points to there either being a hard pan at the bottom which is not letting the water through - could be a hard surface left behind by the builders or a badly compacted area such as a compacted layer of clay - or on the other hand the water table might be particularly high there, which no amount of organic matter or grit would sort out. I assume it's not the latter, as I'm sure you would already know about that! Hope this helps. Sarah.

PS in the interests of saving the planet (somebodys got to do it, so it might as well be me) please could I gently steer you away from using peat...? Not only do several species depend upon peat bogs, but digging peat out of peat bogs causes the water table to drop, leaving peat high and dry, which then decomposes, which releases methane into the atmosphere, which contributes to global warming, which is why I have lilly beetles and leek moths devouring my garden as I speak!

18 Oct, 2008

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