From patio to lawn - on clay.

Hi folks, sorry to post another thread about replacing a patio with lawn. I've read previous posts but whilst interesting they still left me with questions.

We bought our house 16 years ago, brand new, and the builder excavated down so that the level of the patio is about 3-4 feet lower than the surrounding land. The "soil" is largely very, very heavy clay. It's that super cold, solid clay which is light blue in colour, sometimes called puddling clay I believe. To make matters worse the area is surrounded by a low brick wall so I guess (I have no knowledge) adding any kind of drainage would be impossible or too expensive.

The patio was laid properly but is now uneven. I think the lack of drainage means the water underneath the slabs freezes, then expands meaning any patio is likely to move. As such I am reluctant to pay for another patio to be laid and my thought is that a lawn might be better. The question is whether it's possible for any lawn to succeed.

I would like to replace the patio with some kind of wildflower lawn.

Would what I want to do be impossible or prohibitively expensive? My thought was to ask a groundworker to remove the patio, dig down so far, remove the clay, replace it with soil and I would then lay rolled turf with wildflowers in it.

Can I ask

1/ Should forget the whole idea? I do need to do something and as I said above I think any patio would move.

2/ How far would we have to dig down and remove clay for this to work?

3/ Would I just put all soil down or a layer of stones, grit or similar first?

4/ The area is about 32 feet x 12 feet.

5/ Any idea of very rough cost for a groundworker/labourer to remove patio/dig out.

Sorry for the long post, any advice very welcome

Dave

 

Puddling clay was used to create a water sealed barrier during the construction of canals etc etc. With the builder excavating an area lower than the surrounding area, they have created a sump. Creating a wildflower lawn is achievable, but the clay needs to be addressed first. You will need to Incorporate a drainage system or incorporate a good volume of sharp sand, grit, composted bark, straw and organic matter first. A good mixture of different size particles is needed, which should be rotavated into the clay before adding a good depth of top soil.

 

Hi gks.

Many thanks. I don't think a drainage system is possible so can you please elaborate on the alternative. How deep should I go, what would be the depth of sand/grit/bark etc and what would be a good depth of top soil?

For example would you dig out 12 inches, then six inches of sand etc, then 6 inches of topsoil? Just a rough guide if poss please.

 

Hi,

Digging out thick clay by hand on that scale would be a back breaking job and to dig out any depth would really need a mini mechanical digger and lots of expensive skips.

As you say the patio was already 3-4 ft lower than the rest of the area, is it possible to just add a depth of good soil and raise the height of the area ?

A photo of the area and surroundings might help us see your situation more clearly.

 

That was my first thought, but then it depends on how close the patio is to the property.

 

I will try to add a photo. It shows my wife working on it (I did too!). This was ages ago, we went from lawn (which was always wet in the shaded area) to patio when we got our dogs. Now only have 1 dog and he's too old to romp about on it so I am OK to go back to lawn, if that's possible. I don't think it would be possible to get a digger in. Maybe 12" was ambitious. I wonder if I could get away with less? Thanks folks.

 

A nice looking garden though not sure digging out would be a realistic option unless you paid for someone to do it, though assume you will have to remove about 6" depth of the old patio and its foundation layers ?

If you than added in about 9" of top soil think we would give that a try as you are not looking for a bowling green lawn.

Regardless of any depth of clay you removed the basic problem of a being a sump and some excess dampness will remain.

Would hang on and see if one of this sections lawn experts @Liz the pot comes in to offer any good advice.

 

Many thanks for your time. As you say I'm not looking for a bowling green, rather something presentable which will attract bees/birds etc.

Just a final question - is there a kind of wildflower turf which thrives in damp conditions? I guess that would help.

Ta.

 

Hi,

Not sure about wildflowers, sure someone will offer some advice.

 

I think it will all work out fine.

Wildflowers do best in poor soil, because in good soil the grass will just take over.

You can buy wildflower meadow seed mixes from various companies online. I'd stay away from the big name retailers who tend to be more geared towards the hobbyist home gardener, and look at companies aimed at landowners. They tend to have a range of seed mixes specifically blended for different soil types and conditions, and often sell the seed by the kilogramme rather than little packets.

You will still need to do some soil prep, but if it's a wildflower meadow, it shouldn't need to be much more than breaking up the top couple of inches to enable the germinating seeds to get their roots in, and to prevent standing water every time it rains. If it were me, I'd loosen the top couple of inches, drive the fork right in at intervals to make some drainage holes, then cover the surface with sharp sand. For seeding, I've had success in the past by mixing seed with sharp sand and just chucking it over the surface. Then it's just a waiting game.

 

Just my thoughts, but the garden looks a bit formal, do you really want a 2ft high wild flower garden?
Personally I dont think it would look right in that situation.
I'd also say there are poor soils and there is clay, not much grows in clay without the clay being broken up and something incorporated with it, sand grit, gravel or organic matter all of which will help drainage.
But if the site is basically an enclosed sump with no way for water to drain away it will probably become a swamp in wet winters whatever you do.

So my ideal would be give water an escape route, and incorporate something into the clay to break it up and keep it broken up.

 

I wonder if a soakaway would work? Dig out an area about 3 x 3 x 3 ft depth in a central part of the garden and fill it with gravel. This allowing the water to drain away. A potted plant could be stood on top for decoration.

 

That's fair comment Pete, I see what you mean about it not looking right. My thought process was that another patio would just be a costly mistake because the lack of drainage means any flags laid would move sooner or later because the water trapped underneath will freeze in winter, expand and cause movement. That being the case I thought a lawn of some sort would be better and I would like to encourage bees, birds etc into my garden so I thought of wildflowers. I'd be really grateful for any views/opinions.

Thanks again.

 

It's just that I don't see wild flowers as short growing plants, I'm not well up on what is available, I just think in that position it would make the area unusable.
Rather than covering the whole area with slabs what about a mixture of gravel with slabs dotted amongst it where you could place containers with plants that you like and insects like.
Any movement in the slabs would be hardly noticable i would think.

You could even plant some plants in the gravel.

 

That is a very interesting idea Pete. I will get my thinking cap on.

Thanks.