Yes, Osmocote is safe to use around trees and shrubs and the amount depends on the size of the container and plant. Osmocote Outdoors and Indoors (pink label) is an all purpose plant food and the rate is one capful or three tablespoons for a two gallon container or 4 square feet of planting area. This would be a good application rate for your maple assuming it is of average size. Keep growing, Marianne Binetti