Apple rootstocks have traditionally been divided into three groups: standard, semi-dwarf, and dwarf.
A standard size tree refers to trees growing on seedling rootstock. If trees on seedling rootstocks are not pruned to limit tree size, the trees will reach a height of about 30 feet and have a crown diameter of about 30 feet. Orchards planted before the 1960s often had only 40 trees per acre and were spaced 40 feet by 40 feet. With good pruning, standard size …