What is a dwarfing rootstock?

Apple seeds that are planted do not produce a replica of the type of fruit that was planted; therefore, trees must be propagated by vegetative means such as budding or grafting. Typically, they are grafted onto a rootstock, which is just another apple selected for certain characteristics, such as dwarfing and/or disease resistance. (But not eating quality!) The rootstock provides many benefits to the finished tree. The most important one is ultimate tree size control.

In apples, tree size has been classified as standard or seedling, semidwarfing, and dwarfing.

  • Standard rootstocks produce the largest trees and can be as tall as 35 feet.
  • Semi-dwarfing rootstocks are intermediate between standard and dwarfing rootstocks and can produce trees that are 16 to 35 feet tall.
  • Dwarfing rootstocks produce the smallest trees and range from 6 feet tall to 12 to 14 feet tall.

In general, trees that are on dwarfing rootstocks require some tree support such as stakes, a trellis, or a conduit with a single wire. Modern orchards are rapidly converting from standard and semi-dwarfing rootstocks to dwarfing rootstocks because most of the work such as pruning and harvesting can be handled from the ground or on short ladders. See information in the Apples resource area on this website or the TRECO Nursery rootstocks page for more information about dwarf rootstocks.

Answer provided by Dr. Robert Crassweller, Penn State University.