These are usually trees that were cut back at planting time to force low growth. Cut back new growth by half now, and again in late summer. Cut back new growth by half in spring and late summer as above. In the first two years especially, cut back vigorous varieties as often as necessary. Do not allow any variety to dominate and shade out the others.
Second year pruning is the same as the first year.
Cut back new growth by half in spring and late summer. In the third year choose a height and don't let the tree get any taller. Tree height is the decision of the pruner. When there are vigorous shoots above the chosen height, cut back or remove them. Remove broken limbs.