Garden Clearance - Clay Layer 12" down

Lailoken

Hi,

First post here as I'm looking for some feedback/advice on gardening project I've managed to get myself into. I'm not a keen gardener, just mow the lawn and strim the edges normally.

Potted history - bought new house 5 years ago and paid for builders to lay the turf. Over the years we've had very soggy lawn (everyone does here as its clay soil - fair enough) plus expanding growth of couch grass which I finally decided to dig up this year. Thought it would be digging up just the clumps but due to the roots I've ended up digging up entire lawn - 17m x 13m area, with a few small decking areas in that. (approx 180m2 total lawn , 3 x 10m2 of decking). The builders as expected left it in a state and dont think it was rotavated never mind stones removal - soil very compact which might be cause of flooding?.

Most of lawn was removed with approx 3 or 4 inches of soil held to it in roots, all thrown away. Rest of roots will be dug out and thrown away as well.

All going well with the project I was planning to turn the next 12 inches of soil then lay about 3 inches of new topsoil and seed it in September ready for next year.

When I've started digging the 12" further down I've hit a clay layer -
hopefully attached imgur link can be pasted by someone so you can see this (I've put space in the http as I have new account) - htt ps://imgur.com/a/Ac4jfBy

I can dig out 8 inches of the clay, but dont have time for that in whole garden so my query is -

Will 12 inches of sub soil plus 3 inches of new topsoil be good enough for the lawn, or is it still likely to flood in patches after all the digging?

Also, if laying stepping stones is it better to lay before I seed the grass or wait for grass to take then lay path of stones?

Grenage

Unless you are removing massive amounts of clay, it's not going to make much difference. My parents filled in an old pond with rubble before adding topsoil and turf - and it helped the garden... a bit. That was 2x2m and 1.5m deep in a small garden.


I'd probably lay the stones at the same time as the lawn, assuming they are flush with the ground.

getmore4less

Looking at the pics and given the size of the plot I think buying/hiring/building a soil sifter and stone remover may be worth considering.

plenty of ideas on youtube


Not sure you need to dig down much further, consider some drainage channels and a soakaway if it got really bad

12 inch prepared cleaned of weed materials and stones should be more than enough along with improver and more top soil is probably over engineering the seed bed for a lawn.

DaftyDuck

Nothing in gardening is ideal, and you work with what you have. Will it still flood? Possibly. But, even if you remove that clay, you have to replace it, which is costly, and you may still need drainage.

I'd recover and see on that. If you do still get puddles, you could buy as petrol auger for a hundred quid (cheap ones do work, but are a beast to handle), and take out some boreholes as drainage, refilling with shingle up to 6".

You could go the whole hog, and stick drainage in. But, if everybody else has wet lawns, all their water bass to go somewhere...

Slabs for path I'd do just before seeding. But, the soil will sink and settle, so you might have to relay them.

Justagardener

Will 12 inches of sub soil plus 3 inches of new topsoil be good enough for the lawn, or is it still likely to flood in patches after all the digging?

The combination of 12" of sub soil and 3" of top soil will be just fine. Don't worry It won't flood. Don't consider putting drainage in, you could regret it when you find out there was no need and have to water like mad to keep it green I the summer

Lailoken

Thanks so much for all your replies, really appreciated and some very good points I hadnt thought of, particularly having to backfill what clay I remove with filller which is more cost, although doing the work myself is definitely saving money as its only 20 tonnes topsoil and then grass seed so far.

Now got the impetus to carry on with original plan, will remove any obvious clay above 12 inches down thats easy enough, but leave below that,, if it still floods in bits I can look at the boreholes next year maybe. noted on slabs as well, was worried about the ground sinking more than the level stepping stones, but can always relay later.

thanks again.