How to Prune Young Shade Trees No.1 Editor: Dr. James R. Fazio • $3.00 An unpruned A 15-year-old shade tree that was 15-year-old shade tree. properly pruned when young. s the twig is bent, so grows the tree.” This insightful old bromide about children might just as well serve as the cardinal principle for pruning young shade trees. What you do to your tree in its first few years of life will “A affect its shade, strength, and even its life span. In importance, early pruning must rank just after selecting the right tree for the site and careful planting. The sketch of the tree on the right represents what What made the difference? we like shade trees to look like 15 years or so after planting: a tall, straight trunk and a full, healthy crown The tree at the right was properly pruned when it with strong, well-spaced branches … a tree that casts a was young. The tree at the left was neglected. broad expanse of sheltering shade, that resists damage by wind and ice, that is easy to maintain. This bulletin explains how pruning young shade trees is a simple, straight-forward task. It is a job The sketch at the left also represents a 15-year-old that needs to be done, whether by you for the trees tree. But it looks more like a big, rambling bush than in your yard or by your community for the trees on a well-groomed shade tree. Its low-growing branches public property. In any case, proper pruning will obscure streets, driveways, and walks, posing traffic save money in the long run and give you safer, more hazards. Many branches have been damaged during beautiful, healthy, easy-to-maintain trees. storms, and weak, unsightly shoots sprout in abundance. Maintenance is badly needed and will now be expensive. A Tale of Two Trees One happy day in May the all-American dream came new starts in life. Unknown to each other, both families left alone, just as it is in the forest. Family B knew The new transplant is probably on poor soil that is then true for two families. Brand new houses of their own in planted trees that were the same species and the same age. better. They realized that a tree in the yard or along a subjected to the trampling of hundreds of footsteps. It the suburbs. The good life for their kids. New friends street is not growing there because ecological sorting most likely is not enjoying the optimum conditions of and neighbors. More space and comfort. And good Looking ahead, we would expect the twin trees to matched its needs to the site. It is there because it sunlight or shade, and it certainly does not have the investments, too. eventually make a nice contribution to the neighborhood, was planted there; nature’s method was circumvented. advantage of forest neighbors to shield it from wind, each spreading its shade to grateful residents for prune its lower branches, and form the outline of its Now, it happened that both families loved trees, so generations to come. But, it was not to be. Unfortunately, crown. In short, it needs help. they each promptly planted one to commemorate their Family A had the misguided belief that a tree should be FAMILY A’S TREE — NOT PRUNED WHEN YOUNG FAMILY B’S TREE — PRUNED WHEN YOUNG AT PLANTING AFTER 3-4 YEARS AFTER 5-7 YEARS 15 YEARS AFTER PLANTING AT PLANTING AFTER 3-4 YEARS AFTER 5-7 YEARS 15 YEARS AFTER PLANTING Family A didn’t ask By the time many The baby is quickly Family A’s tree is now for planting instructions. transplants are in their becoming an adult. The not only unattractive, but Family B also Root growth should be Lower limbs are pruned Family B was amazed to They knew how to plant new homes for two to results of not making dangerous, especially planted their tree well on its way to anchoring off to “raise” the bottom see their tree survive a major a tree. When that was four growing seasons, corrections early in life when the wind is blowing. correctly, but they the transplant and expanding of the crown well out of windstorm one summer day. done, they believed their sprouts and suckers may are now quite visible, Lopsided and dense, the tree also noticed a broken to the size necessary to the way of human heads. While many other trees in work was done. appear. The root suckers although some are in full leaf catches the wind branch and a branch nourish the growing branches. The lowest limbs are now the neighborhood suffered protruding near the still not obvious to the like a sail. Also, the narrow that was competing Family B decides to cut off permanent. An important split tops and broken limbs, Actually, they were base sap strength from untrained eye. To the branch angles and multiple with the leader. the root suckers and sprouts fact is recognized here. theirs stood strong and firm. partly correct. You may the tree. The sprouts more careful observer, leaders have resulted in Both were pruned in the crown. Excessive Branches do not move Proper pruning gave strength receive instructions to are disproportionally the form of the future a weak top. The broken close to the trunk. branches are thinned to upward as a tree grows to the branches and allowed the contrary, but little vigorous and weakly crown is apparent. branch not only attracted Another, swollen reduce competition for light, taller. The center of a the wind to pass harmlessly should be done to the attached to the tree. And insects, but may soon break from the sting of an water, and nutrients, and a branch at 5 feet will always through the thinned crown. tree at this stage. In look at the broken limb. off under the weight of too insect laying eggs (a codominant leader is removed. be at 5 feet. Early each spring, the tree most cases, it is best to By now, it has sprouted many sprouts. Decay has gall), was snipped A few of the lowest limbs are gets scrutinized and dead leave all the leaf surface numerous branches just entered the trunk where off. Otherwise, also removed, but others are Higher up, a few or damaged limbs are cut possible to manufacture below the break — too the little bent branch tore all branches temporarily left to help the overzealous branches are off using proper pruning food that will build a many, in fact. off many years ago and a were left intact to trunk develop more taper and cut back so they do not methods. Otherwise, Family larger root system. It has jagged stub protrudes just provide maximum strength. Growth is far enough protrude beyond the outline B has only to enjoy their been found that both above it. The tree is an leaf surface to along to reveal branches that of the crown. A branch here tree. And what do you roots and top will be accident waiting to happen. manufacture food rub or are growing in an or there is removed for more know? Just before they larger after one year if It is becoming more of a during the first undesirable direction. Narrow even spacing, but basically moved recently, the realtor left unpruned. liability than an asset for year of life in its angles are also eliminated for the job of sculpturing the told them it was their trees the property. new home. reasons explained on page 4. tree is now complete. that helped sell the property so quickly. 2 • TREE CITY USA BULLETIN No. 1 • Arbor Day Foundation TREE CITY USA BULLETIN No. 1 • Arbor Day Foundation • 3 Pruning for Strength Pruning for Form The first guide to pruning a young shade tree is to have a clear understanding about what pruning can do for The objective in pruning for form is to help shape a the tree — and you. tree that is aesthetically pleasing and serves well in the space it is to occupy. After pruning with strength in mind, For example, we know to prune modestly — if at all After the first year, pruning should begin in look for ways to help shape the most desirable tree. — when transplanting a new tree. An immediate objective earnest. Pruning with strength as the objective is must be to strengthen and expand the root system which the best way to avoid weak branches later on and is often reduced by 80-90 percent during transplanting. To to prevent expensive corrections that will otherwise 2/3 meet this objective, as much as possible of the leaf surface become necessary. (the tree’s food factory) is left intact. Only damaged or dead limbs should be removed. What to look for: WATERSPROUTS AND BRANCH ANGLES AND SIZE Narrow angles signal a SUCKERS point of future weakness, whether in the trunk or These “parasite” sprouts crown. As the two branches can occur at the base or Before After Pruning Pruning grow, neither has sufficient inside the crown. They are space to add the wood rapidly growing, weakly 1/3 needed for strength. attached, and upright. Instead, they grow against Usually they use more each other. The effect is energy than they return similar to hammering in to the tree. It is best to a wedge. To prevent this remove them as soon THINNING AND SPACING INGROWERS, PROTRUDERS, AND CROWN RATIO and the expensive problems as possible when it is that are sure to follow, obvious they are Most trees benefit from thinning — removing a When a crown is dense, look for limbs that turn simply remove one of the vigorous sprouts.