Question re clay soil

This is a garden in southeast London.
We have a hard clay soil.
I plan to plant in the area edged blue on this photo.
My question is : would you dig out/remove a further layer of soil before adding compost/top soil to the level of the patio? Or would you just add compost/top soil now?
I want to create the best structure for plant root growth.
Thank you.

 

Hello and welcome to the forums.
I'd leave it there but, have to dig it over for drainage and dig in a lot of compost and topsoil, make sure that it's good topsoil to put in.

 

Hello and welcome to GC If you're prepared to break up that hard layer and mix thoroughly with manure, grit and/or compost to another spade's depth, it'll give your plants a good start. On the other hand, if you've got to do the hard graft anyway and can afford the quantity of good topsoil and compost required to fill the bed, it would probably be easier to get rid of the clay. The main thing is to ensure that excess water can drain away, otherwise you'll end up with a bog garden

 

I'd be inclined to break up the soil we can see there at the moment and then fill with topsoil.
The worms will then take some down into the clay over a period of time and stop the clay forming a hard pan.

 

Also mix in some manure worms love it.

 

Not sure of the depth of soil involved, it looks like 2ft+ going on top, personally I'd put any manure in the topsoil, most plants feed nearer the surface and only go for achorage and water lower down.

 

If you're planning to fill it right up, I'd say it's deep enough as it is without digging further down. No harm would be done by going deeper, unless you find cables or pipes, but I think it's effort for little value.

It's already deeper than the top soil layer in many gardens. My subsoil is about a foot down, and I have no problems.

 

I think the breaking up is just to improve drainage and create a more natural soil structure.
If just left a hard base you get no connection between top soil and subsoil and it's almost like a big container.

 

Tap rooted plants will find a way to bust into the clay at the bottom.

 

Yes they will, but this is why new build houses always have a problem with drainage, they dump fresh free draining top soil on a hard pan of clay, it then turns into a wobbly jelly once you get heavy rain, and there is no connection between top soil and subsoil.