I want to create a small area (2 square meters) for new plants and/or seedlings. I need to raise a level in that area a little (for overall garden design purposes), and I plan just to put 30cm / 1ft high layer of mixture of soil and compost to that area.
(the existing grass would be mowed prior to adding the new layer)
Is this plan good or bad? Do I miss something? Will the existing grass, and its roots, negatively impact new plants?