I forgot to add I live in NC red clay. I am planning on digging down and adding compost to my soil below. I would love to just dig out and throw away my clay and replace with good soil but would this create a soggy bathtub? I also have plenty of leaves left to fill the hole with.

I used 8X8X16 cinder block last winter as my first layer. It did ok. I was concerned that the 8 inch depth wasn't deep enough so I have double staked so they are now 2 blocks high. I don't fill in the dirt completely so I assume the dirt is 12 inches deep.

Tomatoes, beans, and everything else is almost perfect height for picking.

When we lived in Atlanta area, that red southern clay? Tomatoes LOVED it!! We had the biggest harvest ever.

Good luck