This is particular true of genetically improved maple planting stock, which is usually available only in limited quantities. When maples are 18 inches in diameter, there should be between 40 and 50 maples per acre. Ideally, these should average about 33 feet apart. To provide some selection as the trees grow, smaller trees should be planted at either 11' x 11' spacing or 16.5' x 16.5' spacing. If maples are planted at wide spacing, interplanting of a nurse species, such as black locust or European black alder, should be considered.
Nurse trees help control weeds, improve crop tree form, and reduce wind.
Some, such as the two mentioned above, are legumes and enhance soil fertility. As the maple trees attain larger size the nurse trees are removed. Larger, wild-grown maples can be transplanted in either early spring or late fall. In most areas throughout the commercial maple range smaller bare-rooted seedlings should normally be planted only in the early spring to reduce the risk of frost heaving. Lifting and moving of this size seedling will require some power equipment, as it weighs nearly 300 pounds.