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Sandy topsoil and clay subsoil


We bought our first house in late August and we've started tackling the garden to create a haven for wildlife and us.

We started digging our pond straight away and a large border to grow a mixed native hedge. 

The soil is a very sandy topsoil of about 1-2 spades depth. Then thick yellow clay!!! I've only ever gardened on sandy soil before. 

Do I need to be careful with what we plant here? I brought lots of plants with us, over 100 eek. But I'm not sure if they'll like this soil combination? 

We do want to add organic matter, but it's going to take a lot to improve that clay layer and time too!

Any advice would be appreciated. 


  • PosyPosy Posts: 3,601
    I think that if you have 8 - 20 inches of topsoil you should be ok as long as it drains. I live in an area of heavy clay and native hedges love it. You could improve the sandy top layer with lots of organic matter but I can only see a problem if the ground stays very wet all winter.
  • TopbirdTopbird Posts: 8,192
    edited March 2019
    From my own experience of gardening on clay I think (but I don’t know!) that your main problem could be with areas of compaction. 

    I have one area which has taken alot of trampling & a digger working on it from a couple of hard landscaping projects. The top 18” is now (lots of organic matter) quite nice crumbly soil but there are still a few pockets of deeper solid compacted yellow and grey clay.

    As a general rule, when you’re planting shrubs and trees I think you’ll be ok so long as you dig and improve the soil deeply and thoroughly - especially if you’re planting in areas where people have been walking or standing. I think your native hedge will be fine - mine thrives on clay. It’s mainly hawthorn planted as whips.

    Do a particularly thorough job if you’re planting shrubs which don’t really like wet feet. I lost a buddleia 2 years ago when it was very wet. When I dug it out the roots were just embedded in a mass of wet sticky clay.

    Get loads of organic matter dug in. If you have new or completely clear borders you could consider double digging....😕. It’ll come good over time🙂
    Heaven is ... sitting in the garden with a G&T and a cat while watching the sun go down
  • Thanks to you both. We didn't have that wet a winter here, and the clay isn't holding water. So hopefully it's still draining well. 

    The hedge whips are all planted, we dug down very deep, because there were 5 concrete lumps from previous fence lines which had been buried! We've added compost to the top, so the worms can carry the goodness down. 

    We also have foundations and a low brick wall to dig out from under the lawn, also been buried. grrrr

    Yesterday I started digging the area for our new birch tree, and found more buried builders rubbish. They'd just grown a Hebe on top of it. So task today is excavation of that whole area.  
  • LoxleyLoxley Posts: 5,401
    edited March 2019
    I don't see any particular problem. The fact that the clay is yellow would indicate it's not stagnant and sodden (in which case it would be grey). The yellow indicates the presence of oxygen. I wouldn't worry about improving the clay subsoil if it's 1-2 spades down. Get organic matter in at the top and let the worms get to work.

    Presumably you can grow shallow rooted plants that prefer light sandy soil alongside deep rooted plants that prefer clay soil!
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