Training a young tree: five years of small cuts for one leader, no narrow forks and a clear trunk

A young tree’s frame is set in its first five years, with small cuts that cost it little. The aims are one leader, side branches spaced along the trunk and no more than half its width, and no narrow forks with bark trapped in them. The lowest limbs come off a few at a time, until the trunk is clear to the height the site needs. Cut nothing at planting but dead or broken twigs, start training in the second or third winter, and never take more than a quarter of the live crown at one time.

What to cut at planting

At planting, cut off only dead or broken twigs and any that rub. The old advice to cut back the top of a new tree, to make up for roots lost in the digging, has not held up:

“Thanks to research in the past 20-30 years, it was discovered that compensatory pruning did more harm than good for the tree.” (Penn State Extension, Making Sure Your Young Shade Trees Survive)

The buds at the shoot tips make auxin, a hormone that starts root growth in spring, and the leaves make the food that builds new roots. Trees whose planting cuts take only weak, dead, diseased, rubbing or injured branches grow faster afterward and establish sooner.

Leave the low branches too, even the small ones along the trunk. They thicken the trunk at its base for a sturdier, better tapered tree, and they shade young bark against sunscald.

Start training in late winter of the second or third year, once the tree has recovered from the stress of the move, as the care calendar sets out. Guides differ on one case. NC State Extension advises making the structural cuts at planting when no one can return to the tree within a year or two, while the wounds are small. Blue Whale Trees sells most of its trees as seedlings and young saplings, and a tree that small is far easier and cheaper to train than a grown one.

One leader, and what to do with its rival

Most young trees grow one dominant upright stem, the leader, and training keeps it in charge. Never cut back its tip, and prune back any side branch that grows taller than it. Two stems of nearly equal size rising from one fork are called codominant stems, and no branch collar forms between them. In a pulling test of 100 branches on ten red maples about 10 years old, Edward Gilman of the University of Florida found:

“Codominant stems were far easier to split apart than branches that were small relative to stem size.” (Edward F. Gilman, Branch-To-Stem Diameter Ratio Affects Strength of Attachment, 2003)

The codominant stems split at the union, down the trunk, while the small branches broke near their collars. The angle of the fork made no difference to its strength.

To choose the leader, compare the two stems just above the fork. Keep the thicker, straighter one, nearer the center and free of wounds. Remove the rival at the fork while it is small, which leaves the smallest wound. Once it is too big to take off without a large wound or a large share of the crown, shorten it instead. A reduction cut takes it back to a side branch at least a third its diameter, which slows the rival so the leader outgrows it.

A leader lost to a deer, a mower or a storm is replaced by shoots from the buds below the break, often two or three at once. Keep the strongest, straightest shoot and treat the others as rivals. A conifer that grows no new leader by itself can be given one. Tie a top branch upright to a small stick with soft ties, and take them off before the next growing season.

Some natives need almost none of this. Bald cypress and black gum need no pruning, and sourwood shapes itself.

Narrow forks and branches too big for the trunk

The larger a side branch is next to the trunk, the more easily it separates, so keep each permanent branch to half the trunk’s width or less, both measured just above the union. Past two-thirds of the trunk’s width, a branch is more likely to split. Shorten the largest branches first, back to a side branch.

The angle matters through the bark it traps. In a narrow V, the bark of each stem is squeezed between them as they thicken, and this included bark weakens the union until it may fail as the tree matures. Choose branches that leave the trunk at 45 to 90 degrees, and take out a narrow one while it is small. On a fork that already holds bark, shorten or remove the stem that is not the leader. Multistem or single stem shows how to spot trapped bark on a trunk that looks like one.

Space the permanent branches 18 inches to 3 feet apart, up and around the trunk, and never let one grow directly above another. These natives fork young and need training most:

• Black oak: young trees tend to fork, so thin a double leader back to one early. Zones 3 to 9, 50 to 80 feet.
• Northern red oak: young trees tend to fork, so keep one central leader. Zones 3 to 8, 50 to 75 feet.
• Shumard oak: young trees often fork, so keep one leader and the side branches under half the trunk’s width. Zones 5 to 9, 50 to 80 feet.
• Winged elm: prune three or four times in the early years, to one trunk with wide-angled limbs. Zones 6 to 9, 40 to 60 feet.
• Yellowwood: its low, narrow forks split in storms, so train it in midsummer, since winter and spring cuts bleed. Zones 4 to 8, 30 to 50 feet.
• Live oak: prune every year for the first three years, then every five years to age 30. Zones 7 to 10, 40 to 80 feet.

Raising the crown a little at a time

The lowest branches on a young tree are temporary. They stay while the trunk thickens, then come off from the bottom up over several years, each before it is an inch thick. Leave a cherrybark oak its lower limbs for a few years to build caliper.

How high to clear depends on what passes beneath. About 8 feet serves over a lawn or a walk, the street side of a street tree may need 16, and a screen or windbreak keeps its branches low. The lowest branches left are the tree’s lowest for life.

Keep live branches on at least the upper two-thirds of the tree’s height. A trunk cleared to 8 feet therefore needs a tree about 24 feet tall, so a smaller tree is raised over several years. Our growth estimator puts a 3-foot northern red oak past that height in about eight years on an average site, and a white oak in about 22. A crown raised faster leaves a trunk with less taper and a tree more likely to fail in high winds.

Pin oak keeps its lower limbs, which droop as it grows, and an open-grown swamp white oak keeps its low limbs too. Raise either a little at a time, in the dormant season, where the limbs would be in the way.

Five winters at a glance

The training runs about five years, and no winter’s cuts take more than a quarter of the live crown:

After the fifth winter, a structural check every three years until the tenth year, and every five years after, keeps the frame.

When in the year to cut

Make training cuts in late winter, before the buds break. The frame shows without leaves, and a cut made weeks before growth starts begins to seal early in the season. Oaks have a firmer rule where oak wilt occurs. Sap beetles carry the fungus to fresh wounds, so cut no oak from April through July, or from February through June in Texas. A red oak infected through a branch can die in as little as four weeks.

Maples, birches, yellowwood and hornbeam bleed sap when cut in late winter. The bleeding does them no harm, and a cut in the coldest part of winter or after the leaves have fully opened avoids it. Trees that flower in spring set those flower buds the year before, so shape them right after they bloom.

Your tree this winter

Start with the tree in front of you:

• Find the leader and any rival before the buds break, and step back to look at the tree from all sides between cuts.
• Count the years to a clear trunk for your own species in the growth estimator.
• Make each cut just outside the branch collar, with three cuts for any limb the hand cannot hold, as pruning at the branch collar shows.
• Ask before a cut you doubt. Send a photograph of the fork and one of the whole tree through the support page.

Common questions

Should I prune a newly planted tree?

Only to remove dead, broken or rubbing twigs, since its leaves make the food for new roots. Begin training in late winter of the second or third year.

Which leader should I keep on a young tree?

The thicker, straighter stem nearer the center, compared just above the fork. Remove the rival while it is small, or shorten it to a side branch so the leader outgrows it.

Why are codominant stems bad?

Two stems of nearly equal size split apart far more easily than a branch smaller than the trunk. A narrow fork between them often traps bark, which weakens it further.

How much can I prune off a young tree at once?

No more than a quarter of the live crown at one time. Keep live branches on at least the upper two-thirds of its height.

Sources

• Making Sure Your Young Shade Trees Survive: Penn State Extension (Vincent Cotrone, updated 2024): the old advice to cut back a new tree’s top for its lost roots and the research against it, auxin from the shoot tips and the leaves’ food for new roots, and the quotation.
• Pruning Young Trees: Iowa State University Extension and Outreach (Jeff Iles, reviewed 2024): faster growth when planting cuts take only weak, dead, diseased, rubbing or injured branches, low branches that thicken and shade the trunk and come off from the bottom up before an inch thick, two-thirds of the height left as crown, major limbs 24 to 36 inches apart, and laterals kept below the leader.
• Pruning Young Trees: International Society of Arboriculture (2021): pruning at planting limited to dead or broken branches with the rest withheld to the second or third year, the leader’s tip left alone, codominant stems removed or shortened young, included bark in narrow unions, spacing of about 3 percent of mature height, a sturdy tapered trunk from secondary branches, and clearance of 8 feet, or 16 on the street side, with screens branched low.
• Tree Pruning Essentials: Purdue Extension (Lindsey Purcell, FNR-506-W, 2015): structural pruning in the first five years and its smaller wounds, the dominant stem chosen and rivals removed or subordinated by reduction cuts, permanent branches half the trunk or less, a quarter of the green tissue at most, live crown and taper, gradual crown raising, the lowest branches kept for life, and spring bloomers pruned after flowering.
• Branch-To-Stem Diameter Ratio Affects Strength of Attachment: E.F. Gilman, Arboriculture & Urban Forestry 29 (2003): the pulling test on 100 branches of ten red maples, codominant stems split at the union while small branches broke near the collar, angle unrelated to strength, and the quotation.
• General Pruning Techniques: NC State Extension: structural cuts at planting when no one can return within a year or two, branch angles of 45 to 90 degrees, no collar on codominant stems, and reduction cuts to a lateral a third to half the size.
• Principles & Practices for Pruning Trees: Clemson Cooperative Extension, Home & Garden Information Center (HGIC 1003, revised 2019): the straightest and strongest leader, branches under two-thirds of the trunk’s diameter less likely to split, and weak crotches under 45 degrees.
• How and When to Prune Trees: The Morton Arboretum, with its page How to Prune Evergreen Trees and Shrubs: pruning in late winter while the structure shows, callus started early in the season, the trees that bleed and when to cut them, and a new leader tied up on a conifer.
• Oak wilt in Minnesota: University of Minnesota Extension: no oak pruning from April through July, sap beetles drawn to fresh wounds, and a red oak infected through a branch dead in as little as four weeks.
• Chapter 9: Tree Health Care and Pruning: Virginia Cooperative Extension, Tree Steward Manual: a structural check every three years until the tenth year and every five years after.
• Prevent the spread of oak wilt in Texas: Texas A&M Forest Service (2025): no pruning or wounding of oaks in Texas from February through June.