Hi Marcy,
It would be useful to know your context. It would be a different proposition between, say, West of Scotlant and East Anglia, as to how dry you are or whether you can put enough water down!
There is a garden called Glenwhan (https://glenwhangardens.co.uk/) in the South West of Scotland where parts of the garden are only a few inches of peat over solid rock. This could be equated to by compost over concrete. However, that part of Scotland receives a LOT of rain ….
My response would be suck it and see 🙂 !
