We are starting a new garden in our new house. I purchased Robert Chapman Heather/Calluna vulgaris 'Robert Chapman', Dwarf Alberta Spruce/Picea glauca 'Conica', and Dwarf Female/Skimmia japonica. These will be in our bed in the front surrounded by pink mountain rocks. What kind of fertilizer is good for these plants and what should I do to prepare the ground underneath these bushes to give them a jump start to a great life? Thanks, Knapp