Young apple trees should only be pruned selectively for shape. Try for well spaced, evenly arranged branches. Trees with trunks less than 5 cm in diameter should look like fat Christmas trees, with the young branches alternately arranged around the full 360º of the central trunk. Cut off any crossing branches, those too close together, and any little twiggy things coming off the trunk.

By the time they are 15 cm in diameter, they should have a main structure of 4-6, evenly spaced main branches, about 50-70 cm apart on the main trunk. The lowest one can be quite low on the trunk, if easy picking and maintenance is paramount. Or the branches can start above head height, to double as an ornamental in a garden. This "modified central leader" training provides the strongest structure to resist wind and heavy snow loads, that is still open enough to allow the light penetration and air circulation necessary for disease control and ripening.

If your area doesn't have heavy snow, you can train it to have 3-4 branches about 30 cm apart, in an open bowl shape--trained low, you can sit in the crotch of the tree, while you take a break from picking! This method has the advantage of quick ripening, and very easy spraying, pruning, and picking. On the other hand, extra fruit thinning may be needed in some years to prevent breaking branches. This is called "open center" training.

Once the tree is mature, little pruning is needed, though fruit size and quality can be improved by selectively thinning out 1/10 of the thumb-thick branchlets, encouraging a constant succession of new branchlets with vigorous new fruiting spurs.