1. Control the growth of large lateral branches: American red maple must control the growth of large lateral branches regardless of the balanced development of seedling crown. If the diameter of the base of the big lateral branch exceeds 1/3 of the diameter of the trunk of the seedling, it should be re-cut (mainly including thinning and re-cutting) to inhibit the growth of * * *. American red maple was trimmed into a beautiful crown.

2. Moderate thinning: The basic balanced seedling crown is mainly moderate thinning in plastic surgery. Sparse the branches, opposite branches, whorled branches and too dense cross branches that grow vertically and vigorously from the trunk of seedlings, so as to avoid destroying the normal crown shape and trunk shape as much as possible. It is also necessary to remove branches that grow weakly and have pests and diseases in the crown. 3. Restrain the strong and help the weak: the crown of uneven development is mainly to restrain the strong and help the weak in transformation. In winter, vigorous branches and upright branches can be properly thinned, and the opening angle of the lateral branches can be increased, and then the back branches can be replaced with heads, and the weak buds or weak branches can be cut short to weaken the growth of the excessively strong lateral branches. For weak lateral branches, it can promote their growth, sparse dying and dead branches, reduce the opening angle of lateral branches, replace the head with upright branches, adopt moderate short cutting and leave full buds in the incision, which can promote the growth of new shoots of American red maple.