Bonfire last autumn now wood ash/earth bed - What to plant ?

I had a bonfire with a load of sticks from the lopped trees and ivy etc last year which created a base of wood ash . I have now dug it up and created a nice round bed with a mix of earth and ash.
I believe the wood-ash will create an alkaline "earth" and wonder what should be my next move.

Perhaps planting hydrangers is a possibility but would prefer a spot of advice before bashing ahead (which is what I usually do !!!)
Cheers