My house was built in 1952 and the basement was dug out from under the house at a later date. The way they did this left a perfectly sized (approximately 12"x40", about 4' from the floor) space with red clay, which I have 3 bags of good soil (50 quarts each) I plan to displace/augment that with. Presumably, there is no foundation beneath this column of clay - which is enclosed with mere cinder blocks - but I don't quite have a way of determining that definitively.
My question is: assuming I don't grow anything very tall - should I just dump the soil on top of the clay? or should I use the plastic from the bags of dirt (or something more durable) as a parchment? I don't plan on planting anything that would threaten cinder blocks, although I definitely plan to make a question about that, later (we're limited to cat-friendly plants, so).
Or, perhaps I'm a lunatic for wanting to plant in this space, and you good people would rather discourage me from doing so.
Any which way, I'm happy to hear any thoughts & opinions...
EDIT This is what the space looks like: