Clay soil - what else should I do (if anything)?

GayleT83 · September 2020

Hi there, I've viewed the forum for a while but this is my first time posting anything.

We moved into a new build recently and as is fairly typical the soil in the back garden is heavy clay and does not drain particularly well. We are taking things step by step at the moment and have dug out a border in one particular corner. It was dug out earlier in the summer and we've noticed a lot of standing water in the border after it rains. Following advice on here we added 8 50l bags of manure from the local garden centre and I ran our tiller through it this afternoon to break it up and mix it all in. Should we add anything else? Do we add plants/shrubs and a tree now or would we be better waiting until spring so we can see how it fairs over the winter months and add more manure in the springtime?

Image: https://us.v-cdn.net/6030279/uploads/editor/9s/kqbyrptqxsul.jpg

rachelQrtJHBjb · September 2020

With clay soils a pan can form under ground, making it almost impermeable. Given it is a new build it is possible it has been compacted by machinery. If drainage is an issue I would dig down to see if there is a clay pan and, if so, try and break it by digging. Double digging may be an option. The other thing to consider is whether your garden is lower than the surrounding ones, meaning their surface water drains into your plot and pools every time it rains. If drainage remains a significant problem, you could think about raised beds. Even raising the ground by the height of a sleeper on edge (roughly 20cm) you will overcome a lot of the problems associated by water-logging.

Biglad · September 2020

This summer I've dug out a side border that has always suffered from waterlogging, possibly for similar reasons @GayleT83. Nothing planted there has survived for long. I went down about two feet and got rid of a load of stones (NDN was creating a rockery

) and some of the compacted clay (along with all the other strange assortment of debris that's probably been there for nearly 40 years). It was the consistency of hard cheese

. I've just finished mixing some of the remaining clay soil with horse manure, home-made compost (with a load of worms in it) and MPC. The trench has been refilled and appears to drain well. Time will tell but I'm expecting a bumper crop from the strawberries that I've planted in there.

I'd guess that what you've done so far would improve things and the manure will work its magic over time (unless there is a bigger underlying drainage issue). What to plant and when is way over my pay scale on here, though

Don't worry - some proper gardeners will be along shortly!

JennyJ · September 2020

Autumn is a good time for planting most things, but it would be a good idea to wait until you've had some heavy rain so you can see whether the drainage issue is fixed.

Fairygirl · September 2020

The difficulty is that, as already said, you could still have poor drainage there, but some substantial shrubs and trees will help to soak up excess water and get rid of the problem. You won't really know until you plant into it. Catch 22.

As @JennyJ says though - wait until you've had some hefty rain, and see what happens. It sounds like you've done all the right things, so with a bit of luck, it might be fine, but as @rachelQrtJHBjb says - a very simple raised bed will help eliminate any existing problem well enough to allow scope for lots of plants.
One thing I would recommend though is, have you lined the base of the fence in any way? Having wet soil against the wood isn't great, but I can't tell if it's still below the bottom of the fence. It's hard to see from the photo. You'd certainly need to do that if you have the border raised.

Clay soil - what else should I do (if anything)?

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