water logged clay garden

shirleyf1984

Hi, new on here. My son has moved into a new build with garden which was once a pub car park. He has about 8 inches of top soil under which is a thick layer of orange clay, no idea how deep the clay goes. He's planted up two borders removing as much clay as possible (digging down a couple of feet), put down a layer of pea shingle and compost on top.  Unfortunately the clay has now turned the borders into a clay pot retaining the water and turning the compost into a bog garden.  The soil does eventually dry out but its been so wet his plants  have started to suffer.  Any suggests as to what he could do?  Other than completely digging out the clay which would be too costly for him the only solution we can come up with is raised flower beds.  His next-door neighbour has 4 mature trees along the border but even they don't soak up the water.    

amancalledgeorge

Happy to be corrected but the only thing you can do is keep mulching with compost and manure and it will eventually get improved. It would probably been better to mix the grit into the native soil instead of putting a layer which essentially creates a sump for the water to be held in and creating root rot. 

I suppose the best advice to everyone is avoid new builds...few seem to have any regard for proper landscaping. 

Fairygirl

I'd agree with @amancalledgeorge. The soil needs amending before you plant unfortunately, or you need raised beds, which is often a lot easier.
I have both scenarios in this garden. When I moved in 8 years ago, the enclosed part of it was like a car park - just gravel and slabs over solid, sticky clay. The rest beyond the 'enclosure' was grass. I took the internal enclosure away , fenced the boundary, and stripped the turf off the grassed area. I then added loads of manure and left it till the following spring for planting. The 'car park' had the slabs lifted where I wanted beds, and I built raised beds. With the addition of plenty of compost when planting anything, both areas are fine. 
I recently made a new pond, and having to dig down into that sticky clay to create it and put planting in was hellish. 
I'm afraid there isn't a quick fix with sticky clay. 

shirleyf1984

Thankyou both for your advice.  Removing the clay isn't really an option as too costly and the amount to take away would be incredible.  I think best bet would be for him to have raised borders.  I'm imagining the cheapest option for him would be railway sleepers as he would need a decent height for the beds.

Chris-P-Bacon

shirleyf1984 said:

  I think best bet would be for him to have raised borders.  I'm imagining the cheapest option for him would be railway sleepers as he would need a decent height for the beds.

It would. And then add plenty of organic material & plants that like damp soil. There's many to choose from - 'right plant, right place' - job done! 

Fairygirl

I wouldn't necessarily pick plants that like damp soil. Once you have a decent medium in the raised beds, they drain more quickly, even in wetter areas like mine   
I grow all sorts of plants, including those that like quite dry conditions. The more plants you have, the better the take up of moisture too. 
It's also worth lining the beds too, to prolong the life of the timber. Then a bulk load of soil [depending on how many beds and their size ] plus rotted manure and compost. All of that will give a good medium. I also used some of the turf I'd lifted from other areas, in the base, as it's expensive filling deeper beds. If you know anyone who is wanting rid of turf, it's worth getting it. 

shirleyf1984

Thanks for advice.  Has anyone put in a French Drain or similar drainage pipe in very wet soil?  Wondering if this might be a cheaper easier option.  The clay is a solid layer so could the drainage pipe be put on that as thats as far down as the water seems to be soaking which is why the soil above is so wet, the  water is sitting there to be either evaporated or the plants taking it up.

Loxley

You can lay perforated pipe in a gravel filled trench but it needs to drain to an outlet - a low spot in the garden you can accept being waterlogged, a pond, ditch or drain. Personally, I would embrace it and grow astilbes, eupatorium, rodgersia, persicaria, darmera, filipendula, iris sibirica/ensata etc etc etc. So many wonderful plants for damp soil. It's orange clay rather than grey, which shows it's oxygenated even if it seems very claggy and wet.

shirleyf1984

There is a surface drainage pipe across his garden on the edge of the patio, put in when house built so maybe we could use that to drain.  The other thing I thought of was there is a small wildlife area at end of the border, could he put in a container buried in the soil for the water the drain into and so create a wildlife pond. 
Thankyou for the plant suggestions I will pass the list on to my son and its definitely something for him to consider.  Its a shame as he has gradually planted up his garden taking into account plant soil types but this year his garden has been so bad some of the plants are suffering.  Last year wasn't so wet and the plants came through but this year is so wet.  

Fairygirl

You could certainly do something like that and have a pond/bog area. If he wants an actual pond though, he'd certainly need a drain so that water can go in directly. 
It would just be a question of picking the plants to suit. If you get years when it's drier, some plants may still not do so well, and will only thrive if the ground is always damp, so it's a case of doing a bit of research. Some will like a sunnier site and some will need shade, and some will need lots of room.  There are lots of plants which will do perfectly well, especially once established. 
The ones @Loxley mentions are all great. I'd add Acteas, Polemoniums,  and Dicentras [now called Lamprocapnos  ] for shade, and Ligularias for sun. All will appreciate soil that doesn't dry out. Trollius [chinensis in particular] is another good plant - sun or part shade is fine for those. 
It's certainly disheartening for him @shirleyf1984. Fine if you have an endless supply of money and time to replace plants, but most of us don't have that luxury. I hope you can get the problems resolved and he can get a good result with a few tweaks here and there. 

shirleyf1984

Oh thanks Fairygirl.  He never showed the slightest interest in our garden until he got one of his own and now its become a real hobby of his.