Pruning Trees & Shrubs
Most trees and shrubs will require some pruning as they grow to keep them healthy and to maintain a pleasing appearance.
We've organized our tips and techniques into the following categories, and you can link directly to any one of them or scroll down to read them one by one.
Know When to Prune: Most trees and shrubs can only be pruned at certain times of year, usually when they're dormant. Shrubs that flower in the spring should only be pruned after the flowers fade, while shrubs that flower later in the summer should only be pruned in early spring.
Use Proper Tools: Pros recommend pruning shears with curved blades. They do less damage to branch ends. Use lopping shears for branches a quarter-inch to an inch thick. Over an inch thick, use a bow saw.
Follow Proper Techniques: First, thin out dead, crossed and misdirected branches, cutting those back to the base. Then, head back the branches as needed to shape, always cutting just above a bud on the outside of the branch to encourage outward growth.
Choose a Pruning Style: For low maintenance, you'd choose natural pruning which relies mainly on thinning to keep a shrub or tree healthy and to let it grow in natural directions with minimal shaping. Formal pruning also uses thinning techniques to keep the plant healthy, but gets to be more work heading back branches as often as needed to maintain a shape it wouldn't naturally assume.
Pruning Mature Trees
Before you start pruning, look at the tree from a few angles and decide what you'd like to accomplish.
That could be to change the shape, raise the crown, open up the center or any number of things.
Whatever goals you set, you should remove any dead or crossing branches. They hinder a tree's growth.
You should also eliminate branches growing at narrow angles to the main vertical branches. They form narrow angle crotches that are much weaker than joints formed by branches growing at wide angles.
TIP: When cutting off a branch, always leave the branch collar intact, the thickened area where it joins the trunk. But if stub is long enough to hang a hat on, then you haven't cut enough.
Try to work slowly, thinking about your cuts and their impact before actually doing them. A second opinion is often valuable, so you might work with a partner.
Pruning Young Trees
With younger trees, the goal of pruning is to help it develop a true leader branch, a main stem growing straight up that defines the tree's vertical structure.
Your task then is to define the strongest, most vertical of the branches and head back (cut short) any others that threaten to sap the leader's food and energy.
On main branches other than the leader branch, you'll also want to define the main growth, and head back the smaller branches growing off those.
Before pruning a shrub, you also first decide what you want your cuts to accomplish.
As with trees, you should remove any dead or crossing branches. And most shrubs do require occasional thinning, especially the older ones.
When you thin a shrub, you remove the oldest branches right down to the ground. That opens the center of the shrub to sunlight, encouraging new branch growth and increased leaf production throughout the shrub.
The key is to remove those branches totally. Many homeowners never really thin their shrubs, relying instead on periodic shearing of the branch ends.
That encourages heavy leaf production at the branch ends, which prevents adequate leaf production inside the shrub and results in leggy shrubs with long bare stems and dense surface growth.
When shrubs are left to their own devices, the oldest branches and stems will actually turn woody, and that's not good because woody branches do not produce as many leaves and they start to look like trees.
You can put your fastest-growing shrubs on a 3-year renewal cycle so that the stems and branches are never more than 3 years old!
During the first year, remove one-third of the shrub's branches and stems, cutting them right back to the base and focusing on the thickest, woodiest and oldest ones.
During the second year, remove another third of the growth, again focusing on the oldest branches and leaving the new growth alone.
During the third year, remove another third, cutting out the last of the old growth left after the first year of pruning and again leaving the new growth alone.
During subsequent years, remove the old growth as needed but basically taking out the oldest third of the growth and leaving the youngest, most productive branches.
With slow-growing shrubs, the 3-year cycle would probably mean death, but a 5-year renewal cycle (taking out the oldest fifth of a shrub's growth every year) should work for most of them. (Check with your local nurseries for info on your shrubs.)
Pruning Formal Hedges
To turn a row of unruly shrubs into a formal hedge will probably require a couple seasons and several sessions of pruning, but here are the general steps:
Thin out the dead, crossed and unsuitable branches, cutting them right to the ground.
Use long-bladed shears to cut about 6 inches off the tops of the shrubs, leaving a flat surface.
Trim the sides back to create a flat plane, but flare out slightly away from the plant as you go down so it's wider at the bottom than the top. That will expose the bottom to more sun and encourage leaf production top to bottom.
Once it's close to what you want, quit and let it grow for a month or two. Don't overdo the first cut.
When you come back for the second cut, trim the top and the sides back again with the long-bladed shears to remove the wild ends but leave as much of the new growth as you can.
At some point, you can determine the final size and shape of the hedge and then focus your pruning on keeping it that way.