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Hi,
since you guys are always so helpful I thought I’d try you. Google won’t provide a consistent answer.
i have a garden bed. It’s between a render wall and a concrete slab. I’ve established it has no drainage and I can’t see an option to drain it besides onto public land. So no option. I’ve dug clay out about 400mm deep throughout. Getting no where besides a tower of clay sitting in my courtyard I dug a hole about a metre deep in the section I was up to to sus out how much I’m dealing with. I’ve got a slab of orange clay, possibly all the way to China (and bricks I’m guessing the builders dumped). I tried gypsum a year ago, no wonder it didn’t work. Next I dug a shallow trench against the render and filled it with water, just to see where the water went. There’s one section it pooled and didn’t absorb at all. Given its 30 degrees the trench stayed pretty wet all along for an hour or so and has stayed soggy. That’s after removing about 15 barrows of clay and putting a 200mm layer of so of dirt back over. I was thinking try gravel ‘graves’ but reading other posts here it sounds like that’ll just create swaps.
So.. if wanting to grow roses, azaleas, petunia type plants - if I compost over the clay and put 600-700mm of dirt over the top, and then plant and mulch will the plants survive with the soggy clay deep below? Or do I need to go higher with the soil? Or am I fighting a losing battle? I don’t think I can bare digging out any more clay. No clue how I’m going to dispose of it. Cheers
Hi @Gerdener_Yoshi,
If you can manage at least 500mm of soil beneath your plants before hitting the clay layer, there’s a good chance your plants will survive, especially if you improve the soil with compost and organic matter to increase its structure and drainage. However, if you find the soil level too shallow, you could consider adding 200mm-high sleepers around the perimeter to raise the soil level, giving the plants more space to root by creating a raised garden bed.
The key is ensuring the roots have room to grow down and aren't sitting directly on the soggy clay, which could limit their growth and lead to root rot.
Please let me know if you have any questions.
Mitchell
