Spur strains of a cultivar may grow 60 to 70 percent as large as the non-spur strains of that cultivar. Spur-type strains produce fruit at an earlier age than standard strains. Spur-types, because of their compact form of growth, are ideally suited for home gardeners with limited space. Several varieties are available in spur and non-spur strains. Other factors that will have an influence on ultimate tree size include general care, variety, soil type, earliness of fruiting, location within the state, and timing and severity of pruning.
Rootstock influences apple size.
Standard trees are propagated on seedling rootstock and produce large trees that may get to be 15 to 20 feet tall. The most common semidwarf rootstocks used for apples in South Carolina are MM.106, MM.111 and M.7. Trees on M.7 will produce the smallest trees in the semidwarf category while MM.106 will produce trees nearly as large as trees on seedling rootstocks. True dwarf trees will be about 30 to 40 percent as large as standard trees and require support by a trellis or post. The most common dwarf rootstocks are M.9 and M.26.