In my experience (i.e. neither opinion nor fact), nothing breaks clay as effectively as frost.
I add compost, rotted manure and bark chippings to my heavy clay, I don't dig it, I do sometimes chop it up to give the frost more surface area to get at. I add grit very locally when I've got past stage 1 (pot clay), stage 2 (heavy clay soil) and reached stage 3 (clay soil) if i'm planting something that likes free drainage and I'm planting it on a slope (where it won't form a sump - pockets of gritty compost in an area of clay soil will fill up with water on a level bed).
In my experience adding grit to either stages 1 or 2 is very hard work for almost no return and therefore a poor bargain. I've never tried vermiculite - it's far too expensive to use in sufficient quantity. I just grow plants that are happy in clay, of which there are many.
Last edited: 23 February 2018 15:17:23
Gardening on the edge of Exmoor, in Devon
“It's still magic even if you know how it's done.”
When I came to my present garden I found that there was, effectively, no top soil at all. The ground had been used as grazing some years before and was just solid clay, waterlogged in winter and concrete hard in summer. There were lumps of rock and chalk in it but no organic matter and almost no worms, I discovered the sump effect quite quickly and set about learning what to do, given a high water table. My beds and borders now have lovely, friable soil full of life.
So, what did I learn to do that makes me so confident? First I mark out the area to be made into a bed and remove the grass, then, working a section at a time, I dig out about 12 to 18 inches and break the base clay to prevent a pan forming. After that the clay, mixed with muck and grit, can be replaced, breaking up lumps as I go.
When the whole area is done I leave it to weather down and then pile more muck on top and mix that in. I like to end with a surface about 6 inches higher than the ground but that is only because of the water table making drainage a problem. At this stage it can be planted and regular mulching continues the improvement.
I don't usually insist on on my knowledge over anyone else on this site, but in this case, I really do know what I'm talking about.
An elderly neighbour told me it would take forty years to get it right, but it didn't - not quite!
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That may be so but muck and grit are better improvers for clay. They are easier to handle, too because they don't blow away in the wind.
So, if it's windy, add water.
I don't think expressing opinions as facts is very helpful in a public forum. An IMHO perhaps?
It’s not exactly a sensible option given the price of it though ducks. It’s double the price of every other option.
Last edited: 23 February 2018 14:12:53
Well, no. An opinion is a matter of debate. A fact is a fact.
In my experience (i.e. neither opinion nor fact), nothing breaks clay as effectively as frost.
I add compost, rotted manure and bark chippings to my heavy clay, I don't dig it, I do sometimes chop it up to give the frost more surface area to get at. I add grit very locally when I've got past stage 1 (pot clay), stage 2 (heavy clay soil) and reached stage 3 (clay soil) if i'm planting something that likes free drainage and I'm planting it on a slope (where it won't form a sump - pockets of gritty compost in an area of clay soil will fill up with water on a level bed).
In my experience adding grit to either stages 1 or 2 is very hard work for almost no return and therefore a poor bargain. I've never tried vermiculite - it's far too expensive to use in sufficient quantity. I just grow plants that are happy in clay, of which there are many.
Last edited: 23 February 2018 15:17:23
“It's still magic even if you know how it's done.”
Thanks for the info!
learning loads!
polb, us gardeners are always learning loads.
None of us know it all.
When I came to my present garden I found that there was, effectively, no top soil at all. The ground had been used as grazing some years before and was just solid clay, waterlogged in winter and concrete hard in summer. There were lumps of rock and chalk in it but no organic matter and almost no worms, I discovered the sump effect quite quickly and set about learning what to do, given a high water table. My beds and borders now have lovely, friable soil full of life.
So, what did I learn to do that makes me so confident? First I mark out the area to be made into a bed and remove the grass, then, working a section at a time, I dig out about 12 to 18 inches and break the base clay to prevent a pan forming. After that the clay, mixed with muck and grit, can be replaced, breaking up lumps as I go.
When the whole area is done I leave it to weather down and then pile more muck on top and mix that in. I like to end with a surface about 6 inches higher than the ground but that is only because of the water table making drainage a problem. At this stage it can be planted and regular mulching continues the improvement.
I don't usually insist on on my knowledge over anyone else on this site, but in this case, I really do know what I'm talking about.
An elderly neighbour told me it would take forty years to get it right, but it didn't - not quite!