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Conflicting advice on drainage and soil


We're planning on removing the paving and slate chips of the house we've moved into, with the hope of laying turf and raised beds. However, I've received conflicting advice from 2 professional gardeners.

Our garden is flat, 9m long X 4m wide. We're in London, so it's a thick clay soil and it faces North North East.

Ok, both gardener A and B suggest putting the garden on a slight slope when we lay topsoil, so that rainwater can run back towards the house where there are French drains at the patio.

Gardener A said to excavate down 20cm of the current matter which is sharp sand, before we lay topsoil. Thankfully, there was no builder's hardcore. Gardener B said no need, as the sand will help with drainage. This one is important because it either involves a lot of digging and large amounts of waste removal - or not!

Gardener A said lay a channel drain under the soil (I am clueless about these - where does the water end up?).  B said no need. 

A also said to mix some compost or manure in with the topsoil to condition it for drainage. B said no, turf is best without compost as it's too crumbly.

Finally, A said to get a fencer to add gravel boards before we have the topsoil delivered, and B said to affix them afterwards.

Can anyone help? Both are professionals! Thanks 


  • Firstly, water running towards the house always concerns me, because the onus is on you to keep the drainage channel clean. Still, not impossible.

    I don't think the sand will matter, if it's the original subsoil, because it will aid drainage. Do make sure it's sharp sand and not the yellow stuff that builders use for cement, because the yellow much has salts in it which will kill plants. 

    If the garden is prone to waterlogging, then a land drain/french drain might help, but properly cultivated soil under the grass will drain evenly anyway.  

    Re compost, again, properly cultivated topsoil is fine.You can feed the lawn next spring once it's established. If it's to be done now, it won't need much food and the compost is unnecessary, to my mind.

    Gravel boards will be easier to fix before the topsoil is brought in because the soil will bring up the levels and make it more difficult for the fencer to do his job, I'd have thought.

    That's what I think.


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