Pruning Primer - Heading Back
Heading back is the selective cutting of a terminal shoot or branch back to a lateral bud; it causes vigorous new shoots and denser foliage to develop. Head back the branch to about 1/4 in (0.6 cm) above a bud that is facing the direction you want the new shoot to grow.
When pruning a shrub, always head back shoots to several different heights so that you don't produce a top heavy plant with dense outer foliage that shades out lower growth. Never "lop" off branches all at the same height unless you want a shrub with all the foliage densely clustered at the top, and bare stems below. When you head back branches to different levels you produce a fuller and more natural looking shrub.
Heading back the terminal shoot of a young tree will cause the leader (main trunk) to branch - but note that you may get more new leaders than you want, so be ready to thin out the extras.
The pear tree in the photo would have a long, whip-like main leader and just a few very long whip-like branches if it had not been headed back over the past several years.
The main leader (trunk) of this pear tree has been headed back twice, resulting in a shorter tree (easier to pick the fruit) with a greater branch density (on which to produce more fruit).
This lateral branch has been headed back to a bud causing it to grow a more vertical branch. This serves to keep the tree from sprawling, constrains it to a smaller space and produces stronger branches that can more easily support the weight of the fruit.
Heading Back Pines
To produce denser growth in pine trees, cut off one-half of the terminal shoot (the "candle") before the needles begin to elongate in early spring. This causes new buds to form and produces a more compact, denser plant. Never do this at other times of the year because new buds will not develop.
Steve Christman 3/6/01; updated 12/26/03, 9/21/15