The cuts you use to prune result in different growth patterns. The differences lie in where the cuts are made on the stem in relation to dormant buds and side branches.
Thinning
— Cutting off a shrub or tree branch where it originates on the parent branch. These cuts can also shorten branches by cutting to a crotch, where the branch forms a Y. The terminal bud of the remaining branch assumes dominance and stops other dormant buds from growing into branches. Drop catching is thinning the major branches of a tree. This maintains the tree’s natural shape while dramatically reducing its size.
Thinning shrubs reduces their size without stimulating excessive growth. The plant is controlled and rejuvenated for a healthier, stronger and more vigorous shrub.
Heading
— This involves cutting a branch to a stub, lateral bud or lateral branch with a small diameter. Heading a large branch is referred to as stubbing. Since this process removes the terminal bud, dominance is lost. Under the cut location, many vigorous new shoots develop from existing buds. Buds lower on the branch may not sprout. Fruit trees can be headed to encourage branching and counter their natural tendency to produce very few side branches. Trees are often headed under utility wires to remove interfering branches. This typically destroys the tree’s natural shape as well as spurring a resultant rush of new growth.
Shearing
— Similar to heading, shearing removes short lengths of top growth. It can occur above or below a bud, often resulting in a stub. This removes all terminal buds on the stem tips, which sparks a flush of new growth right behind the cuts for a dense exterior canopy. Shearing works best for topiary and other formal hedges. Shearing can ruin shrubs that don’t adapt well to this procedure.
Pinching
— Pinching off the tip of a succulent stem spurs growth, much like heading on branches or deadheading on annuals or perennials. By pinching 1 to 2 inches of new growth, you can encourage the branching of the terminal, or leader, shoots of young trees. You must thin the resultant growth as branches start to grow, or they’ll compete with the main leader.