Philosophy of Pruning Trees
A properly pruned tree looks as natural as possible; that is to say, the tree’s appearance reflects its fundamental form and character. The pruner must be sensitive to maintaining this structural integrity, in addition to knowing a bit about tree biology and proper pruning principles!
Recommended Pruning Equipment
- Hand pruners (Felco or ARS type, bypass, not anvil type)
- long-handled loppers, 18-inch (Corona type, bypass, not anvil type)
- hand-saw, 12-16 inches
- bottle of rubbing alcohol or 10:1 diluted bleach
- whetting stone/sharpener
- safe ladder (3-legged are best for uneven ground)
- pole pruner, 10-foot (optional)
- chain saw (optional)
Tree Pruning Priorities
- Maintain health of tree
- remove all dead, dying, and diseased limbs
- remove crossovers, which can rub together and damage limbs and harbor disease
- remove hazardous branches before they fall
- correct and repair damage.
- Raise the canopy to increase pedestrian, vehicular, or visual zone.
- Rejuvenate the tree by the removal of old wood in such a way that encourages the formation of new wood (remove no more than 1/3 of the wood in one year).
- Improve the aesthetic quality of the tree and thus, its value.
- Slow the tree’s growth by timely removal of foliage (but best to select right plant for the site).
- Fruit trees:
- increase fruit production
- develop strong 45-degree angles to support fruit load
- remove limbs that grow down or straight up
- maintain tree size (5-10’ is ideal size for home orchard in terms of accessibility)
- maintain fruit spurs.
When to Prune Trees
The best time to prune trees is generally during the dormant period, usually in late winter (November– March). However pruning can be done year-round, as needed; for example, dead or diseased branches can be removed any time, the sooner the better. When pruning trees, keep this in mind: Pruning done during the dormant season tends to have an invigorating effect on tree growth. Pruning done during peak growth times tends to slow growth by removing leaves that manufacture nourishment, but too much summer pruning can damage a tree. Pruning during the spring (post-dormancy) and fall (pre-dormancy) is generally the least desirable time as the plant is most vulnerable during those times.
Generally, berries and tree fruits are pruned November until bloom; prune blooming ornamentals during and immediately after bloom.
Sooner rather than later: When you cut away part of a plant, a wound is left, susceptible to pests and diseases. To avoid trouble always prune so as to make small wounds, rather than large ones. Removing a bud or twig produces a smaller wound than waiting until it is a large limb! Rubbing off a sucker bud leaves a smaller wound than if you wait until it has a year’s growth or more!
Heading vs. Thinning Cuts
A tree’s response to a pruning cut depends on where on the branch the cut is made. Both types of cuts are used in pruning fruit trees and grapes.
- Heading Cuts: Several buds left on the cut branch grow, making denser, more compact foliage on more branches. (Figure 1)
- Thinning Cuts: Branches are removed entirely, leaving no buds to grow. Their energy is diverted into remaining branches, which grow more vigorously. (Figure 2)
Angle and Placement of Cuts
Always make cuts close to a node. Branches grow only at these nodes, and if you leave too long a stub beyond the node, the stub will die and rot. (Figure 3)
Prune to the lateral bud that will produce the branch you want. The placement of that bud on the stem points the direction of the new branch. An outside bud, pruned with a slanting cut just above the bud, will usually produce an outside branch. A flat cut above the bud allows two lower buds to release and grow shots.
Pruning Thick, Heavy Branches
- Undercut the bottom of the branch about 1/3 of the way through, 6-12 inches out from the trunk (Figure 4, a).
- Make a second cut from the top, about 2-inches farther out from the under-cut, until the branch falls away (Figure 4, b).
- Cut back the resulting stub to the branch collar (Figure 4, c) (not flush with the trunk).
Anatomy of a Fruit Tree
- Crotch: The angle where branches fork, or where a main limb joins the trunk. Strong crotches are wide angled, 45 degree; weak crotches are narrow.
- Scaffold: The main limbs branching from the trunk.
- Watersprout: A very vigorous shoot from a dormant bud on a branch. Remove by cutting.
- Sucker: A vigorous shoot from the roots or from below the bud union. Cut off at the base. (To remove, dig out soil around sucker, clip the sucker off and leave cut exposed to air.)
Parts of the Branch
- Terminal Bud: The fat bud at a branch tip will always grow first and fastest if you leave it. Cut it, and several buds will grow behind it.
- Leaf Bud: Flattish triangle on the side of a branch. To make one grow, cut just above it. Choose buds pointing outward from the trunk so the growing branch will have space and light.
- Flower Bud: Plump compared to leaf buds and first to swell in spring. On stone fruits they grow alone or beside leaf buds. On apples and pears they grow with a few leaves.
- Spur: A short twig on apples, pears, plums, and apricots that grow on older branches, produce fat flower buds, then fruit. Don’t remove them.
- Bud scar: A ring on a branch that marks the point where the terminal bud began growing after the dormant season. The line marks the origin of this year’s growth.
Types of Tree Forms
- Central leader: one dominant trunk all the way to the top; strong, good light penetration; difficult to reach higher branches with large trees
- Modified central leader: central leader trunk to 6 to 10 feet, then multiple leader; combines strength of central trunk with sun-filled center of vase shape
- Vase shape or multiple leader: vase shape with many branches; short trunk of about 3 feet with three or four main limbs, each of which has fully filled-out secondary branches, creating an open center allowing light to reach all branches
- Others: include espalier and trellis
Training for a Vase Shape
- First dormant season: After the tree has grown through the spring, summer, and fall and into its first winter dormancy, choose three or four branches with wide (45o) crotches, looking for branches that radiate evenly around the trunk. Try to have at least 6” vertical distance between branches, with the lowest branch about 15-18” above the ground. Cut off the vertical stem just above the top one. (If there are fewer than three good branches, head cut the vertical stem and choose the remaining scaffold branches during the next dormant season.)
- Second dormant season: If necessary choose the remaining scaffold branches and cut off the vertical stem just above the highest selected scaffold branch. Remove the weakest side branches from the scaffold branches chosen last season, leaving the main stem and laterals on each branch.
- Third dormant season: Now is the time to thin surplus shoots and branches. Select the strongest and best-placed terminal shoot near the tip of each scaffold branch, as well as 4-6 other side shoots on each scaffold (branch). Leave the short weak shoots that grow straight from the trunk, to shade it and help produce food for the tree.
Frequently Asked Questions
Should I remove my big old apple tree?
Keep it if it has sentimental value, produces good fruit, shades the house, houses a swing or tree house for the kids. Otherwise, remove it and replace it with several dwarf or semi-dwarf fruit trees. The ideal tree for the home orchard is 5-10 feet, because at that height, you are best able to prune, spray, thin and harvest.
(See also EC 1005, Pruning to Restore an Old Apple Tree)
Is it okay to prune suckers and watersprouts? When and how do I do it?
Such overly vigorous growth can be controlled by early summer pruning, which discourages them from regrowing; cut them off at the base. Better yet, rub them off with your thumb in May/June. Watersprouts will emerge following an overzealous dormant season pruning job; sometimes it’s best to leave one or two of these, particularly as a replacement for the leader if it was cut, to discourage regrowth of the others.
Do I need to paint the wounds with a sealing compound?
No, this is no longer recommended. The tree or plant is best protected by proper pruning technique and timing. Sealing compounds encourage wood rot.
How can I slow the growth of a tree?
It is always best to select the right tree for the site, rather than try to work against nature. However, these techniques will help to retard the growth of a tree:
- Reduce dormant pruning; prune more in June/July. (Winter pruning invigorates a tree; summer pruning decreases vigor and size.)
- Give no or less nitrogen. Give less water.
- Hand pull the water suckers in May/June, when they are 2-4 inches long and flexible; this makes it less likely they will regrow. (Pruning suckers in the winter insures they will regrow in the spring.) Leave a sucker on top of the tree to dominate, called apical dominance.
Should I prune a fruit tree when I plant it?
In digging up a young tree from the nursery, some of the root system can be damaged; top pruning is usually required to prevent tree stress due to the lack of balance between the root system and the top. However, excessive pruning of young trees may delay blossoming and fruiting.
For a single whip, prune tree to waist height at planting. Branching will begin at this pruning cut.