Posted: 07/08/2013 at 12:38
I wouldnt worry too much about roots going too deep. They will venture down to 60 cm and more anyway.
The worry would be.....as I see it.....if you ate anything there. So wouldn't put fruit or veg there. You didn't plan on edible stuff anyway, did you?
However you choose to plant your site ....and I think we have all added our views and they will all be different (thats why all our gardens are unique to us) ...just go about enjoying your creation. no option is perfect.
I suggest you write down all the plants that appeal and then sketch them, discuss them and re-sketch until you are happy with your plans. I would use the remainder of the summer for this and aim for "construction" in the autumn.
You will want to change things from time to time or want to add new plants.....just enjoy the ride.