Hi Khadeejah,
It takes ages for the cardboard to break down.
I have had the cardboard on top and underneath (two different gardens). When it is on top it tends to dry out and can blow away so it needs to be weighed down. When it is underneath compost, it stays put. I put a maybe 2 inch layer of mushroom compost over cardboard in January and the cardboard is still there underneath but there are loads of worms in action and only dandelions have poked through.
I think just go for it. Charles knows what he is talking about and it will work, strange and all as it may seem to some gardeners.
