Pruning Young Trees
When to prune
- Start the first winter after planting your tree, and check in with the structure every winter after. Wintertime is best because the tree is dormant and it's easier to see what's going on when deciduous trees have no leaves.
- Avoid pruning in spring, summer, and fall. However, some cuts can be made at any time of year: pruning off any broken, dead, or diseased branches, removing suckers or watersprouts.
Basic pruning tips
- Stay safe! Keep your feet on the ground. Can't reach it? Avoid the ladder and hire a professional.
- Don't cut more than 25% of the live canopy in any one year.
- Before you start, consider what will be the mature size and shape of your tree. Get help identifying your tree with our online Shady 80 database.
- Select the right tools for the job: bypass hand pruners, loppers, and hand saw. Keep them clean and sharp.
Where to start? The 5 steps of structural pruning
- 1. Remove broken, dead branches, watersprouts, or suckers. This leaves you with a clean slate of good branches to start!
- 2. Select and establish a single central trunk. Prune off competing trunks. Avoid double leaders which are not as safe structurally.
- 3. Select and establish the lowest permanent branch. Look around your tree -- how much clearance under the tree do you want (perhaps 7 feet off the ground), trucks (a tree near a street needs perhaps 14 feet off the ground to avoid traffic), etc.? Tree branches do NOT grow up as the tree grows taller - they stay in place. If you have a small tree, the lowest permanent branch may not be present yet!
- 4. Select the temporary branches. Lower branches left on the tree when young shade the trunk (avoiding sunburn) and promote a thicker, stronger trunk. If temporary branches are too long, cut them to about 1 foot. Then remove them completely in a couple years.
- 5. Select and establish the side branches. Consider how big the tree will get and how much space will be needed between mature branches.
How to make pruning cuts
- Always cut back to 1) a bud, 2) another branch, or 3) the trunk.
- When cutting back to the trunk, cut just outside the branch bark collar (often looks like a turtleneck attaching the branch to the trunk). This allows the tree to close the wound.
- When cutting back to another branch or bud, cut just outside of the other branch/bud (which will then take over and grow).
- When cutting a large branch, use a hand saw with the 1-2-3 cut to avoid tearing the trunk.
- Visit the Urban Tree Foundation website for a complete pruning guide.
What to avoid
- Using paint or sealing wounds - trees will close wounds best when they are cut at the right spot and allowed to roll over the wound.
- Flush cuts right up against the trunk
- Stubs and tears
- Lions tailing - most branches should originate from the middle 2/3 of the trunk or branch. Having all the weight at the top of the tree or the tips of branches is less strong.
Pruning mature trees
Most mature trees should be pruned by a professional. Learn how to hire a reliable tree care company to keep your mature tree in good shape.
Some exceptions of work you might do yourself include removing suckers growing off the roots (can be a sign of stress) or removing mistletoe with a pole saw.
A Short Dictionary of Pruning Terms
- Branch Collar
- The slightly swollen area where the branch attaches to the trunk. When branches die or are removed chemicals in the branch collar wall off or compartmentalize wounds to prevent decay.
- Branch Ridge
- The crotch area between two limbs where bark tissue is pushed up to form a ridge.
- Flush Cut
- Pruning cut made so close to the trunk that it removes the natural protection barrier (branch collar) allowing insects and disease to enter.
- Reduction Cuts
- Cut back to a lateral branch that is at least 1/3 the diameter of the main branch. A method to temporarily lower the height of a tree.
Watersprouts are fast vertical growth that should always be removed
- Thinning selectively reduces the density of the top of the tree and opens the lower canopy to light and air which benefits the inner leaves and can aid the health of the tree.
- Topping is the practice of removing major portions of a large tree's crown by cutting branches to stubs not large enough to assume a terminal role . Tree topping creates weakly attached limbs prone to breakage and creates entry points for insect and disease.
- Reactionary growth resulting from stress. Fast vertical growth that should be removed at any time.
- Wood formed at the branch collar that grows over a cut to keep insects and decay from entering.