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. portion of the limbs that compete for space and light. inward, and those that extend beyond the natural two branches. For strength, Evenly spaced laterals, 8-12 inches apart in the young outline of the crown. Prune at the trunk or down to an tree, is a good rule of thumb to help ensure an ideal appropriate lateral branch. Overpruning can damage or the ideal branching angle RUBBING BRANCHES approximates 10 or “ladder” at maturity. Of course, this will vary by species. even kill your tree. Always maintain at least 2 o’clock. three-fourths of the tree as the live crown. Branches that rub result in wounds, decay, Lateral branches should and notches. Remove one be no more than one-half to of the offending branches. three-fourths the diameter Ideal angles of the trunk. As the trunk grows, it will strengthen TEMPORARY BRANCHES the joint by adding wood Branches below the around the branch — like a lowest permanent branch dowel in a chair leg. can protect young bark from injury from the sun CENTER OF GRAVITY and add taper and strength to the trunk. Particularly in Young trees deformed lawn plantings where lower by wind may be corrected limbs do not block passage by pruning. Move the or tempt vandals, the limbs 15 years after removing low branch tree’s center of gravity to may be left for three to four a point more central over years after planting. Then FUNCTION DOUBLE LEADERS the trunk by cutting back remove over the next two to the leader and laterals on three years, beginning with Temporary Try to imagine what the tree will look like when it Protect the leader from competition. In trees with the downwind side (or the larger temporaries. Don’t Branches is larger. If a limb is headed toward trouble (the house, co-dominant leaders, remove the one with a crook or direction of lean) to more let the temporary branches walkway, sign, etc.), remove as early as possible in other defects, or that creates a lopsided appearance. upright branches. become large and vigorous. the life of the tree. Closure of the wound will be more complete when the limb is small, and it is less trouble Caution: Do not prune too high too quickly. To lift the crown, remove lower Caution: When pruning diseased trees, dip your shears in household bleach before and expense. Remember, limbs do not move upward as limbs throughout several years. No more than 25 percent of the live crown storing or moving to the next tree. Be sure to rinse and wipe dry before storage. a tree grows in height. should ever be removed in an annual growing season.

4 • TREE CITY USA BULLETIN No. 1 • Arbor Day Foundation TREE CITY USA BULLETIN No. 1 • Arbor Day Foundation • 5 Keys to Good Pruning Pruning is a Vital Part of Any Urban Forestry Program

1. Prune early in the life of the tree so pruning wounds are 7. When you prune back to the trunk or a larger limb, A survey conducted by American Forests showed small and so growth goes where you want it. branches too small to have formed a collar (swollen that many of the nation’s urban forests are in serious BALLED & BURLAPPED TREE: Firm soil ball with trunk securely area at base) should be cut close. (Notice in the trouble. To stem the decline of shade trees, more and tied. Do not accept a plant with a broken ball. Do not 2. Begin your visual inspection at the top of the tree drawing of the pruning shears that the cutting blade more communities are engaging in vigorous planting accept a tree with a circling root at the base of the trunk. and work downward. is cutting upward for less effort and a close cut.) programs. The magnitude of this effort may vary from Always carry B&B plants by the soil ball, not by the trunk, Otherwise, follow the rules a few dozen park trees in small towns to the annual stems, or branches. 3. Identify the best leader and lateral branches of good pruning of larger planting of thousands of trees in large cities. In all cases, BRANCH BARK RIDGE (scaffold limbs) before you begin pruning and limbs by cutting just outside the investment is significant. American Forests suggests CONTAINER-GROWN TREE: Avoid trees that are root-bound in remove defective parts before pruning for form. the branch ridge and collar that 20 percent of an urban forestry budget should be Cut outside branch the can. Roots that circle around the edge of the container and at a slight down-and- ridge and collar directed at planting and early care. It follows that the may become circling roots. Always remove can, basket, or 4. Don’t worry about protecting pruning cuts. For outward angle (so as not early care of new trees is one of a community’s best pot when planting. (Cut any circling roots when planting.) aesthetics, you may feel better painting larger to injure the collar). Do not COLLAR ways to maximize its investment in planting. Systematic wounds with a neutral-color tree paint, but the leave a protruding stub. pruning of trees during the first several years of growth For some street planting, such as next to narrow evidence is that it does not prevent or reduce decay. should be an integral part of the program. sidewalks, it may be necessary to plant trees that 8. When simply shortening immediately have high crowns. In this case, the height of 5. Keep your tools sharp. a small branch, make the cut at a lateral bud or A basic mission of the Tree City USA program is to One-hand pruning the lowest limbs should be specified when ordering from another lateral branch (referred to as “head” or encourage ongoing shade tree care. Early pruning is the nursery. However, whether raising the crown during shears with curved “headback pruning”). Favor a bud that will produce part of the care necessary for strong, healthy, beautiful blades (secateurs) the years after planting, or as the trees are grown in the a branch that will grow in a desired direction trees. Of the four standards shown on the back page nursery, it is generally important to maintain a ratio of work best on young (usually outward). The cut should be sharp and of this bulletin, time spent pruning young trees trees. two–thirds green top to one–third pruned trunk. ONE-HAND PRUNING SHEAR clean and made at a slight angle about one-fourth of would contribute to Standard 3 as a portion of the 6. Make safety the No. 1 an inch beyond the bud. comprehensive community forestry program. Within a Tree boards should be wary buyers. Carefully write priority. For high branches tree maintenance program, urban foresters and arborists specifications and be sure an expert inspects the trees use a pole pruner. A major POLE PRUNER have suggested that the following steps be included: before accepting delivery on behalf of the city. After a good job on a big tree should start with good nursery stock, remember — a program of be done by a professional 1. Minimum pruning immediately after transplanting; pruning young trees is a wise, long-term investment. arborist. CORRECT TOO TOO TOO within three years, pruning for strength and form; PRUNING CUT CLOSE LONG SLANTED and every three years thereafter, pruning to lift NOTE: Establishing a systematic pruning program qualifies for eight of ten the canopy of street trees (usually to 8 feet above points needed to receive a Tree City USA Growth Award. Holding a tree-care WHEN TO PRUNE sidewalks and 14 feet above residential streets). workshop or publicizing the need to prune young trees — the right way — This depends to a large extent on why you prune. Light pruning and the removal of dead wood can be done 2. Providing initial training and annual refresher also qualifies for points. Contact the Arbor Day Foundation for a Growth Award application and complete list of qualifying activities. anytime. Otherwise, here are some guidelines, but recognize that individual species may differ. training for crews doing the pruning. Caution: Crews that regularly prune older trees WINTER Pruning during dormancy is the most common practice. It results in a vigorous burst of new growth tend to overprune young trees. Strong, well-developed leader (or in the spring and should be used if that is the desired effect. It is usually best to wait until the coldest part of leaders in a multiple-leader tree). 3. winter has passed. Some species, such as maple, walnuts, and birches, may “bleed” when the sap begins to Stressing tool sharpness and, if necessary, Bright, healthy bark. flow. This is not harmful and will cease when the tree leafs out. disinfective methods. 4. Developing an inventory that is kept up to date Trunk and limbs free of insect or SUMMER To direct the growth by slowing the branches you don’t want or to slow or “dwarf” with all maintenance operations, and future needs mechanical injury. being noted, including pruning. the development of a tree or branch, pruning should be done soon after seasonal growth is Branches well-distributed around complete. The reason for the slowing effect is that you reduce the total leaf surface, thereby 5. Monitor annually and prune on a five- to trunk, considerably smaller caliper reducing the amount of food manufactured and sent to the roots for their development and eight-year cycle. than trunk. next year’s growth of the crown. Ideal spacing between branches, Another reason to prune in the summer is for corrective purposes. Defective limbs can FOR THE BEST START, START IN THE NURSERY at least 8”-12” for most species. be seen more easily, as well as limbs that hang down too far under the weight of leaves. A good tree management program begins with Good trunk taper. selecting good trees. When choosing trees for city FALL Because decay fungi spread their spores profusely in the fall and healing of wounds plantings along streets and in parks and other public Low branches — they are seems to be slower on fall cuts, this is a good time to leave your pruning tools in storage. places, you will want trees with a fairly substantial caliper temporary, but help develop taper, even if they are initially more expensive. Some things to promote trunk caliper growth, and prevent sun damage. Caution: In some areas of the country, diseases or FLOWERING TREES If your purpose for pruning is to enhance flowering: look for: insect occurrence may be affected by the time of 1. For trees or shrubs that bloom in summer or fall on current year’s Wide angle crotches for strength. pruning. Check with your county extension agent, growth (e.g., crapemyrtle), prune in winter. BARE-ROOT TREE: Abundant root growth, fiberous and city forester, an arborist, or a nursery operator to 2. For trees that bloom in spring from buds on year-old wood (e.g., numerous small roots, good color, moist. see if there are any local problems. dogwood and flowering fruit trees), prune when their flowers fade.

6 • TREE CITY USA BULLETIN No. 1 • Arbor Day Foundation TREE CITY USA BULLETIN No. 1 • Arbor Day Foundation • 7 Tree City USA Bulletin ORDER FORM For More Information Name Organization Address On the subject of pruning young shade trees, useful City State Zip information is often scattered throughout books and Phone literature on broader topics, such as general tree care For a complete list of Tree City USA Bulletins and bulk quantities/pricing, or pruning in general. Cooperative Extension in most visit arborday.org/bulletins. 1 Issue states also has leaflets on pruning, although most tend $3.00 ea. to focus on fruit trees or the care of mature shade 1. How to Prune Young Trees 1. ______$ trees. For a list of some of the more helpful books and ---- Tree City USA Annual Report ______other references, please visit arborday.org/bulletins. TOTALS: $

Homeowners can obtain advice on pruning young Tree City USA Bulletin 3-Ring Binder...... $7.95 $______shade trees from their county extension agent, local TOTAL PAYMENT:...... $______arborist, or city forester. Communities can obtain assistance in designing pruning and other community forestry programs from their state forester’s office. Order Tree City USA Bulletins online at arborday.org or send this form and mail with your payment to: Arbor Day Foundation • 211 N. 12th Street • Lincoln, NE 68508 888-448-7337 • (Make checks payable to Arbor Day Foundation) 1925 101

Tree City USA Bulletin © 2017 Arbor Day Foundation. Published by the Arbor Day Foundation; James R. Fazio, editor; Karina Helm, graphic designer; Gerald Pulsipher, illustrator. Technical reviewers for this issue: Gene W. Grey, William P. Kruidenier, and James J. Nighswonger.

THE TREE CITY USA PROGRAM IS SPONSORED BY THE Arbor Day Foundation in cooperation with the U.S. SO SIMPLE, YET SO IGNORED Forest Service and National Association of State Foresters. To achieve the national recognition of The wisdom of pruning young trees is often ignored, being named as a Tree City USA, a town or city must possibly because it is difficult to think ahead and meet four standards: envision what a tree will look like in the coming years. Standard 1: A tree board or department But pruning when the tree is small is well worth the Standard 2: A tree care ordinance effort. Here is what some professionals say about the Standard 3: A community forestry program with an need for more attention to pruning young trees: annual budget of at least $2 per capita You don’t want double leaders on your tree … Standard 4: An Arbor Day observance and If it’s a young tree, you can cut out one of these proclamation leaders. If it’s an old tree and it would ruin its Each recognized community receives a Tree City good looks to take out one leader, you could hire USA flag, plaque, and community entrance signs. a qualified arborist to cable the leaders together if Towns and cities of every size can qualify. Tree they pose a threat to life or property. City USA application forms are available from your state forester, the Arbor Day Foundation at – THE LATE CASS TURNBULL arborday.org/treecity, or your state forestry agency. The Complete Guide to Landscape Design, Renovation, and Maintenance PRUNING OR TRIMMING? Just a few minutes with hand shears could solve a lot of problems later on. Despite common useage of the word “trimming,” – TOM WIENS, CERTIFIED ARBORIST pruning is the better term to use when referring to Arborists could do a great service and gain removing limbs from trees. Pruning is the careful and customers by going through new neighborhoods and intentional removal of selected limbs; trimming implies pruning young trees. indiscriminate removal or shearing to produce a certain – THE LATE ALEX SHIGO, TREE EXPERT AND AUTHOR shape — best reserved for hedges and mustaches!

Published for the Friends of Tree City USA by 50006015