Clay soil and new grass

Help/advice please.

Im a basic gardener.

Im on with a garden "project" which has involved me removing a number of paving slabs and moving them, where the patio was im going to lay new turf.

The problem ive got is once the patio is up ive found the soil underneath is very poor clumpy clay which has just been holding water/puddles when it rains overnight.

Im assuming the roof on the turf will struggle to take to this, what am i best doing. Ive read a couple of conflicting articles. One of them suggested putting gravel/stones in the soil and mix it in to break it up a bit. However somewhere else said this is a big no no. I have a huge sack with old decorative border stones which is going in the skip, should i mix some of this in?

Another article suggesting adding something like hay/straw to the clay

Am i best off digging it up and breaking it up as much as possible then adding a coating of top soil over the top prior to the turf.


Any views opinions or experiences appreciated.

Thanks in advance.

 

I would do this.

Soil underneath patios will be really compacted and lacking in any nutrients.
Dig it over well. Also consider incorporating a bit of compost and then cover the whole lot with a layer of new topsoil.
You can then seed or turf into that.

Grass needs good roots to do well, and you will get a much better lawn if you provide it with a good root run.

Kris

 

Clay soil consists of practically microscopic fragments of clay that lock together to form a layer that inhibts water absortion in comparison to other soils. The particles are much finer than sandy or free-draining soils and can cause issues for grass and many plants, yet are great for some plants (and grass species that you won't want in your lawn).

@Kris Lord suggested digging in compost, which is a great idea and will help seperate the clay particles; they don't bind together as effectively when mixed with fine organic material. The layer of new topsoil is also very important.

Adding stones, some loose hardcore, sand, even gypsum etc into the clay sub-soil should help with drainage, but must be covered with topsoil. Stones etc in the top layer would probably result in expensive repairs to your mower, or windows, car etc if stimming the edges of your grass

 

Brilliant thanks for confirming this.

 

That is a good thought with stones when cutting grass. Hate to shatter the new conservatory windows.... or the neighbours.

 

I will get some bags of compost, how much is needed really? The area i am grassing is approx 4ft x 16ft
Would just a couple of bags of compost do? And a thin coating of top soil.

During my "project" i am digging out an old flower bed, which has had plenty of use would just using this soil do the job instead of compost or with the compost.


If that makes any sense..... its late at work

 

Yes. see if you can till in topsoil/manure and then aerate it.

 

It would be wise to calculate the cubic volume i.e. length x width x height (depth) and add a good bit extra on top.

Buying topsoil in bulk, say half a tonne, will work out heck of a lot cheaper than buying it in bags from a DIY store. You can always use the spare to invigorate flower beds etc. I'd use about a quarter of the topsoil weight for compost and mix them together well.

The topsoil extra bit is because it would also be a good idea to compact it with a roller (but don't go OTT). If you just spread it down and put seed on top, your feet will sink right into it. After a heavy downpour, you could easily end up ankle-deep in mud and the lawn will be trashed.

Also, only buy soil or compost from reputable suppliers as cheaper ones often bulk it up with stuff such as finely ground gravel, stones, bark chippings, not to mention the the potential for uninvited guests to enter your garden... the last thing you need is a 'grow your own Japweed, Horsetail or Ground Elder kit' .