TCA Reference Manual: Planting Trees

Minnesota Tree Care Advisors

http://www.mntca.org/resources/reference/reso_ref_04_plant01.html[11/30/2010 8:36:30 AM]

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Establishing Transplanted Trees:Water You Going To Do?By Rich Hauer

Reprinted from the Minnesota Shade Tree Advocate volume 3 number3.

Healthy trees that mature into legacies do not happen by chance. Askcity foresters and they may say you need to match trees that arebiologically adapted to a site. Hopefully you will also find trees(they're in short supply these days) for the site. Ideally, deliveredtrees must then be inspected to monitor for compliance with treespecifications (i.e., depth to the root system, pests, stem condition)included as part of the bid proposal. Short tree planting seasons aresometimes a barrier. Further, at times poor soil characteristics (e.g.,organic matter, pH, aeration, drainage) at the site need modification.After these hurdles are cleared you still have to plant the tree. Butdoes the job end there?

We can see the scorching in thismaple's leaves, a symptom of stressfrom inadequate watering. But theimpact on overall vitality and delay inestablishment may not be as obvious.

For some planting programs, the project ends after planting. Forothers, trees are periodically watered when maintenance staff are notmowing turf. Others may be more dedicated and water trees weekly.All these scenarios will work during years when rainfall is frequent andplentiful. During normal years, however, even weekly watering ofnewly transplanted trees may not be enough. When establishing treesare subjected to water deficits, growth and function of the leaves,shoots and root growth slows to negligible levels. This delaysestablishment and may even lead to the death of these parts. In theworst case scenario, which too often needlessly happens, a netdecrease in living biomass occurs and the canopy becomes smaller.The tree canopy may now resemble a 1-inch caliper tree rather thanthe planted 2- inch caliper tree. The purpose of this article is to shedlight on recent scientific-based prescriptions for watering trees to aidestablishment.

Water and Tree Physiology The function and growth of plants as suggested by Justus Von Liebigin 1840 (modified later by others) is limited by the factor present inthe smallest amount relative to its minimum requirement. Ample light,water, oxygen, carbon dioxide, mineral nutrients and suitabletemperatures are all important for plant growth and function. Quiteoften, how-ever, plant nutrients (e.g., nitrogen, phosphorus,potassium) are most commonly thought of as factors that limit plantgrowth. While these along with other nutrients are vital for growinghealthy trees, water is the factor that most often limits growth. Inhumid regions, water accounts for approximately 80% of the variationin diameter growth. In arid regions, water accounts for approximately90%.

For the most part, trees can only take up water from soil in proximityto roots. Established trees are in contact with greater volumes of soildue to wide-spreading root systems, and are more capable of



obtaining water. Newly transplanted trees have less soil volumes toextract water. Obviously, trees that have root systems severed tofacilitate transplanting (i.e., bare root, balled & burlapped and treespade) have fewer roots and a smaller soil volume in contact withroots. Containerraised trees also have a small root area to obtainwater even though they are transplanted with the majority of theirroot system intact. In fact, newly planted container-grown treesrequire daily watering the first few weeks following transplanting. Justask a nursery operator how often they water their containerized trees!

After planting, form a berm withmulch at the edge of the root systemto insure water is placed in proximityto their roots.

Is There a Way to Reduce Water Requirements of NewlyTransplanted Trees?The removal of branches at transplanting, or compensatory pruning,was a common practice in the past. The idea was simple: since rootswere removed during the transplanting operation, then the canopyshould be pruned accordingly to compensate for the root loss. It wasthought that fewer branches and leaves meant less demand for water,leading to better establishment. Research from Oklahoma, Coloradoand England have found trees establish more quickly withoutcompensatory pruning when watered frequently. With little rainfall orsupplemental irrigation, trees pruned and unpruned at plantingestablish similarly (See Pruning at Planting, MNSTAC Advocate, Spring1999. Antitranspirants (also known as antidesiceants) have also beensuggested to aid transplant success. Antitranspirants reduce waterloss through stomates by either causing stomate closure or coveringstomates with a waxy film that is a barrier to water loss. In theoryantitranspirants seem reasonable, but in practice they may lengthenthe establishment period. While closed or blocked stomates reducewater loss, they also decrease carbon dioxide entry into leaves. Lesscarbon dioxide accordingly reduces the manufacture of energycompounds from photosynthesis.

But what practices can be used to reduce water requirements oftransplanted trees? Two methods are mulching trees (See Mulching,MNSTAC Advocate, Spring 1999) and planting smaller-sized trees.Mulch helps reduce evaporation from soil surfaces and also addsorganic matter to the soil. Smaller trees establish sooner than largertrees and require less water during watering. In addition, a berm canbe formed at the edge of the root system to insure applied water isplaced in proximity to the roots.

Prescription or Dosage-Based Watering Historically, tree-watering guidelines have suggested watering treesevery seven to ten days with 1 to 1-1/2 inches of water. While thisfrequency and amount of water may work in some situations, researchwithin the last five years from the Morton Arboretum and theUniversity of Florida at Gainesville suggests more frequent watering isnecessary for optimal tree establishment. Within two to three days,rootballs of newly planted trees will dry to levels that impede rootgrowth. Newly transplanted trees in the Midwest will benefit from dailywatering for the first one to two weeks, applying approximately 1 to1-1/2 gallons per-stem-caliper inch per watering. Thereafter, watertrees every two to three days for the next two to three months andthen weekly at the same rate until established.

Remember, newly transplanted trees are absorbing water from adiminished rooting area (i.e., apply water to the root ball). Roots mustgenerate and grow into surrounding soils before a larger soil volumecan be tapped for moisture. Tree roots grow approximately 18 inches



in length annually in the Midwest. Trees in Minnesota will becomeestablished within one to one-and-a-half years for each caliper inch ofstem. Thus, it takes two to three years before a 2-inch caliper tree isestablished. The more closely you match your watering frequency tothe optimum the quicker trees become established.

Labor to water trees is sometimes given as a reason or excuse for notadequately watering newly planted trees. If the water requirements ofnewly transplanted trees cannot be met, planting smaller trees isrecommended. For example, 1- and 2-inch caliper trees have less rootloss and recover faster than trees 2 to 3 inches in stem caliper.Mulching trees to a 2- to 3-inch depth is recommended as it helpsreduce evaporation and conserve precious water. Incorporating thelabor cost of watering trees within the tree planting budget shouldinsure adequate watering occurs and trees establish successfully. Iftree planting is part of the contract process, consider includingwatering as an additional component in the bid. Your communityforestry program will be far better off if trees are adequately wateredrather than if you are continually replanting and not realizing thebenefits that mature and established trees provide.

Irrigation Guidelines for Quickly Establishing Trees (Well-drained sites during the growing season in the Midwest)

Less than 2-inch caliper planting stock Water daily for 1week; every other day for 1 to 2 months; weekly until established

2- to 4-inch caliper planting stockWater daily for 1 to 2 weeks;every other day for 2 months; weekly until established

4-inch caliper planting stockWater daily for 2 weeks; everyother day for 3 months; weekly until established

NotesModified from Gilman, E.F. 1997. Trees for Urban and SuburbanLandscapes. Delmar Publishers. 662 pp.

Delete daily irrigation when planting in fall or early spring. Littleirrigation is needed when planting in winter.

Reduce frequency in cool, cloudy, wet weather if soil is poorly drained(soil drains less than 3/4 inches per hour). Eliminate daily irrigation inpoorly drained soil. Following a rainfall, wait until all free moisturedrains out of the soil.

Establishment takes 12 months per-inch- trunk caliper. Minimumfrequency for survival could be once each week. Irrigation can ceaseonce trees drop deciduous foliage in the fall. At each irrigation, apply 1to 1.5 gallons for each inch of trunk diameter to the root ball.

Rich Hauer is a Professor at University of Wisconsin-Stevens Point:College of Natural Resources



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"We Guarantee Our Trees For AYear." Is That Enough?By Gary Johnson and Andy Sobert

Reprinted from the Minnesota Shade Tree Advocate, volume 3 number4.

Our "disposable, costs- too-much-to-repair, junk it" way of living haspermeated our lifestyle and has influenced our way of thinkingregarding tree selection, planting and care in our urban landscaping.We tend to have the attitude that says, "Plant it now; if it doesn'tsurvive, we'll replace it." This attitude is fostered by warranties ofgarden centers, nurseries and other firms supplying trees to thehomeowner.

"Guaranteed for One Year" is a common warranty offered by tree andshrub suppliers. Most forestry professionals will agree that, evenunder very adverse conditions and with minimal care, most trees will"survive" for twelve months. As urban forestry professionals andadvocates, we need to expand the thinking and the expectations oftree buyers who are offered a warranty of 365 days. Trees should beviewed as permanent structures, especially when put in theperspective of their potential lifetimes. An exercise in humility for allof us might include the estimated longevity or years to maturity forthese selected trees*:

Sequoia - 4000-5000 yearsRed pine - 350 yearsEastern larch - 100-200 yearsBur oak - 600 yearsWhite spruce - 250-300 years

Bur oaks can live over 250 years in Minnesota.

Purchasing quality plants vs. purchasing guarantees At the heart of the issue is the assumption of risk, and the risk in thisissue is whether or not the purchased trees are healthy enough topotentially live long, useful lives in our landscapes. Dick Cross of CrossWholesale Nurseries, Inc., in Lakeville, MN, offered this grower'sperspective of one-year guarantees:

If the tree has the potential to survive (adequate roots, leaves, storedenergy), then the guarantee is adequate. In other words, if the treehasn't been grown well and harvested correctly, it is likely to failwithin that first year and the guarantee is a worthy investment. Theretailer assumes that risk for the first year of the tree's life.

According to Cross, the consumer should examine the trees beforepurchasing them and look for evidence that the tree has been grownand cared for properly. This includes good foliage, intact and healthybark, good over-all vitality if the tree is containerized, a moist, full,and intact (minimum of broken roots) root system if the tree is bare-



rooted, and in general, a 50/50 canopy/stem ratio. For instance, a 10-foot tall tree should have the branches starting at about 4.5-5 feetabove ground.

Based on the research conducted at the University of Minnesota,Forest Resources Department since 1994, the depth to the first mainorder roots (first true branch roots) is equally if not more important tolong term health. Diagnostic root collar excavations and randomizedsampling of three tree species (ash, linden, maple) have revealed thatburied root systems often result in shorter lives for trees. This is aconcern when purchasing containerized and balled-and-burlappedtrees, situations where you can't see the roots. When purchasingthese plants, ask the retailer for permission, to probe down throughthe soil ball with a wire (coat hanger gauge) to find the depth to thefirst branch roots. If the roots are close to the surface, that's good. Ifthey are deeper than four inches from the surface of the soil/root ball,you will be purchasing an inferior root system, especially after youremove that excess soil at planting time.

Guarantees connected to installations Although many guarantees are tied to cash-and-carry purchases,many are also connected to installed landscapes. In these cases, theconsumer purchases not only the tree but the contract to haveitinstalled. Now the risk is not just whether or not the tree is healthy,but also whether it is handled and planted correctly. From hisexperience, Dick Cross believes the way trees are handled prior toplanting, the way the planting sites and holes are prepared and theway trees are finally planted on the, site are all at least as importantas the quality of the plant. Therefore, poor handling and plantingtechniques can lessen the chances of survival for a healthy tree inthat first year.

The error of placing the root (trunk) collar area several inches belowthe landscape grade often results in a condition known as stemgirdling root syndrome, or a general slow decline in health,Unfortunately, based on the research conducted by the ForestResources Department, these problems and subsequent decline oftentake 12-20 years to become obvious ... long after the one-yearguarantee. The trees were healthy, but the handling and plantingtechniques placed the trees at risk for several years.

Marc Shippee, City Forester for Blaine, MN, has encountered problemswith some retail nurseries installing trees on new residential sites, insituations where the installed trees are mandated by the city'sreforestation plans. One retail nursery in particular not only refused topay careful attention to planting depth; they claimed that they'venever had any problems with planting depth causing tree decline inthe 1O year history of their business. Still, they threatened to void theguarantee on the trees if the homeowners or city forester insisted thatthe top half of the burlap, strings and wire baskets be removed.Shippee has taken the position of ensuring long-term health byinsisting that these best planting practices be implemented (properdepth, removal of burlap, strings and wire), and has advocated thathomeowners insist the one-year guarantee be honored.

Will replacement trees fare better than the original guaranteed trees?Possibly not, unless some of the serious conditions that caused thefailure of the original trees are remedied. If the cause of failure was apoor tree, then the replacement tree may do much better (if it's agood one). If the cause was chronically poor handling practices or site



conditions, the new tree probably won't live long either.

To fortify the plant guarantee when the plants are also being installedby a retail company, a consumer may want to develop a detailedcontract between himself or herself and the company. Barb Kirkpatrickof North Oaks, MN protected her landscape investment by addingsome details to the original contract offered to her. She specified thatall trees and shrubs, must have their first, main order roots within oneinch of the soil surface. As the work progressed on the project, shehad to ask the installation contractor on two occasions to add theplanting depth requirement before she would sign the contracts.Whether this oversight was an accident or purposeful, the examplestresses the need for monitoring and double-checking on the part ofthe consumer.

Did Kirkpatrick's contract clause protect her trees? After they wereinstalled, she randomly checked a few plants to make sure they wereplanted correctly. They weren't. In the end, the original contractortook care of a few of the problems, extended the guarantee to twoyears, and just gave up on others. Kirkpatrick had the remaining treescorrectly planted and has since used a different contractor for herexpanding landscape. The new contractor told her "I want to plantlegacies instead of just planting trees," and has abided by the clausesshe has inserted in their contracts.

In summary, Kirkpatrick recommends the following steps whencontracting out tree planting on your own property. You'll betterensure not only the health of the trees, but the handling and plantingpractices:

1. Communicate your expectations with the contractor.

2. Be specific when drawing up the contract and double checkthat all of your conditions are included before signing it.

3. Withhold 50% of the contract balance until you are satisfiedthat the contract has been honored.

4. Perform a random inspection of the installed trees and shrubsbefore the final payment.

5. Hire reputable, qualified and ethical people who care abouttheir reputation.

As Dick Cross also recommended: If you notice a tree is notperforming well, don't wait until the end of the guarantee period andexpect a free replacement. Call the retailer or contractor as soon asyou notice problems because they may be able to intervene and savethe tree.

Buyers must be educated to look past the "One Year Guarantee." Theycan expect much better results if they learn and adopt proven treeselection and installation practices, and assume some of the risksinvolved in creating arboreal legacies.

Gary Johnson is Associate Professor of Urban and Community Forestry,



University of Minnesota, Department of Forest Resources. Andy Sobert is aMinnesota Tree Care Advisor and Member of the MNSTAC Research andEducation Committee.

*(Richard J Preston, Jr.; North American Trees, Fourth Edition)



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Fact or Fallacy: "ContainerizedTrees Are Fool-Proof Trees"By Gary Johnson


Containerized trees and shrubs began to enter most Midwesterngarden centers in the 1960's, offering the potential for extending retailsales and landscape installations beyond the traditional spring andautumn seasons. They also "promised" that transplant shock would beall but eliminated, especially as compared to balled-in- burlap (B&B)or bare-rooted (BR), field-transplanted trees and shrubs. In the pastfour decades, growers have learned and relearned more aboutproducing plants in containers. They've designed and modified thecontainer sizes and, shapes, and are now marketing more trees incontainers than ever before. But have containerized trees proven tobe the green industry panacea for all seasonal, transplant shock andplant health problems?

MYTH: "Containerized trees have 100% of their original rootsystems because they have been grown in containers all oftheir lives."

Unfortunately, this statement is not necessarily true. Somecontainerized trees are truly container-grown, from small seedlings orcuttings to landscape sizes, and do have almost all of their originalroots in the containers. Some are field-grown, dug as bare- rootedtrees and then potted up to be "finished-off." Some containerizedtrees may have been in those large containers for only 3-4 monthsbefore they are displayed in the retail nursery sales lot. They mayhave an adequate root system or they may not have much beyondthose roots that were left on the trees when they were dug from thefields. And some trees and shrubs are field-potted, that is, dug fromthe nursery fields, potted with the same field soil and shipped togarden centers. So, containerized trees may or may not have a betterroot system than B&B or BR trees.

MYTH: "Containerized trees do not suffer transplant shockwhen planted in the landscape."

Most of the transplant shock (reduced health, characterized by smallleaves, chronic wilting, stunted growth, etc.) associated with B&B andBR trees is due to root losses during the transplanting operations.Even if containerized trees have adequate root systems for normalgrowth, they almost always suffer some sort of transplant shock asthey leave the intensive care environment of the nursery, where theyhave received optimum amounts of water and nutrients.

Most container "soils" are mixtures of materials that are optimum forroot growth, holding the right amount of water but still well drained,



and nutrient-rich. Many urban landscapes have compacted soils thatare often poorly-drained and devoid of organic matter, and mostlandscapes are fully exposed to drying winds and full sun exposures.Unless the newly planted trees have been correctly planted, wateredcarefully every few days and the soil deficiencies were correctedbefore planting, these trees will also suffer transplant shock. Theirroots were not removed during the transplanting operation, but theymay die in the harsh environment of the typical urban landscape.

Figure 1. Remove excess soil over themain lateral roots.

Figure 2. make sure the depth of theplanting hole is not any deeper thanthe distance between the root collarflare and the bottom of the containersoil "ball."

MYTH: "As opposed to B&B trees, containerized trees neverhave their first, main roots buried too deeply in the soil."

Containerized trees are just as vulnerable to having their primaryroots buried too deeply in the soil "ball" as B&B trees, and they needto be inspected for excess soil over the roots before planting. Probedown through the top of the container soil level with a coat hangerwire until you can feel the main lateral roots at the point where theyare attached to the stem (root collar flare) (Figure 1). It is not unusualto find four or more inches of soil over those roots in containers. Toavoid future problems that develop when trees are planted too deep,remove that excess soil and make certain that your planting hole isnot too deep. These roots should be at or just below (1/2 to 1 inch)the landscape soil or mulch levels when planting is completed. So, thedepth of the planting hole should be the distance between the rootcollar flare and the bottom of the container soil "ball" and notnecessarily the depth of the entire soil "ball" (Figure 2).

Containerized trees are convenient, less expensive than B&B trees,can be planted anytime the ground is not frozen and are usually easierto handle than B&B or BR trees. The production of trees in containersis a boon for the nursery and landscape industry, and they can beperfectly good trees. But they must be treated as any other tree: buyonly those that you know have good root systems; understand thatthey need at least as much site preparation and care when planted inthe typical landscape; and make certain that those first roots are at ornear the soil surface when you finish the planting process. Your effortswill be rewarded with healthy, long-lived trees that are valuableadditions to the landscape.



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The Right Way To Plant A TreeBy Gary Johnson and Cindy Ash


Trees can be purchased in many sizes, as bare root, containerized orballed and burlapped specimens. Basic planting is the same buthandling and special considerations apply, depending on the size andtype. The inset picture shows the old way to plant a tree. The largerpicture shows the new way to plant a tree: prepare a wide-diametersite and dig a properly sized hole in the center.

Tips for All Trees

Select the right plantfor the site. Base this on the soil type, soilpH, surface and subsoil drainage, and exposure to sun, wind andde-icing salts.

Prepare the site by removing the sod. Loosen the soil by tillingor spading an area three to five times wider in diameter than thewidth of the root system, and only to the depth of the rootsystem.

Dig a hole in the center of this circle that is one foot larger indiameter than the root ball and is exactly as deep.

Maintain undisturbed (not loosened) soil beneath the root ball toprevent the tree from settling.

Carefully place the tree in the center of the hole and double-check that the root collar (lowest part of the trunk, immediatelyabove the uppermost root) is just above the top of the soil. Tip:The uppermost root should be just below the soil surface. Seedrawing for proper depth.

Backfill around the roots with the soil that was removed. Lightlypack or water the soil during this process to eliminate air pockets.Backfill to the height of the root ball, no higher.

MULCH with four to six inches of coarse wood chips or shreddedbark. Pull the mulch back from the trunk to prevent direct contactwith the root collar and trunk.

Water is very important to a newly planted tree. A slow,soilsaturating trickle a couple times a week is a good rule of thumbfor a new tree, but varies depending on soil type and plant size.This should provide the new roots with sufficient moisture without



drowning them. They need oxygen, too! Adjust the wateringschedule accordingly for rain or very dry conditions.

Don't Forget To

Inspect containerized and container-grown trees prior to plantingto see if the roots are pot boundcircling around themselves. (Avoidpurchase of pot bound plants if possible). If pot bound, remove thepot and make a vertical slice up each quarter of the root ball to adepth of about one inch. Cut an X across the bottom of the soilball to a depth of about one inch. Gently loosen some of the roots,then plant.

Inspect bare root trees for broken roots and all trees for brokenbranches prior to planting. Remove any of these with a sharp handpruner. Also, remove crossing or rubbing branches.

Keep all types of root systems moist prior to planting. Moist strawor sawdust works well for bare root trees.

Soak bare root trees in water one hour prior to planting.

Sweat bare root trees in a shaded place such as a garage andkeep them moist until the buds open. Sweating is a process thatcreates favorable conditions necessary for bud break anddevelopment on certain tree species, such as oaks andhackberries.

Remove all containers prior to planting, including biodegradable,paper-mache pots. If the roots and soil are loose in the container,then place the container in the planting hole and carefully cut awaythe container as you backfill with soil.

Be sure all roots extend away from the trunk to prevent futureproblems with encircling and stem girdling roots.

Remove the upper two rungs on wire baskets before completelybackfilling. Do not remove any of the wire basket before the treeis safely in the planting hole and is partially backfilled!

Remove the nails holding the burlap together, then cut away theburlap after the plant has been partially backfilled. Never allow anyburlap to remain above the soil surface.

Cut and remove all twine and rope from around the soil ballafter planting.

Prevent animal damage to young trees by placing a cylinder of1/4 inch mesh hardware cloth around the trunk, leaving two tothree inches between the wire and the trunk.

Tips for Special Situations

For heavy and/or poorly drained soils, plant slightly higher thannormal and mound the soil up, to cover the roots.

Do not add peat to poorly drained, clayey soils, as it can act as a



sump and draw water into the root zone.

Do not add rocks or gravel to the bottom of a planting hole toimprove drainage-unless connected to drain tile.

When using tree spades, water the trees thoroughly before movingthem. Rough up the sides of the planting holes with a shovel orrake, then place the trees slightly higher than the original grade toallow for settling.

If using a weed control barrier, use a porous landscape fabric. Donot use plastic around trees.

Staking: Generally not necessary but if the tree is unstable shouldbe applied to allow for some movement and the REMOVED withinone year. Connect the tree to the stakes with wide (two inches orwider), flexile materials, such as strips of burlap, canvas or oldbicycle inner tubes. Avoid ropes, strings or wires in garden hosesections.

Know Your SoilsTest the soil for pH and nutrients. Contact your local Extensionoffice.

* Test the soil for drainage. Dig a hole 24" deep, and fill it withwater. All water should drain within 24 hours.

* Test the soil for compaction. You should be able to easily digdown two spade depths (about 18"). If the soil is too hard to dig,either don't plant there, or loosen the soil in an area with adiameter of ten feet. Gary R. Johnson is Professor of Urban andCommunity Forestry at the University of Minnesota, Department ofForest Resources.

Cindy Ash is with the United States Forest Service.

Specification graphics modified or taken from "Inspection andContract Administration Guidelines for Mn/DOT LandscapeProjects, 1997 Edition," except as noted.



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Effects of Deep Planting on Long-Term Tree HealthBy Gary Johnson

Tree roots need oxygen and water in order to survive and grow.Because of those basic requirements, the majority of tree and shrubroots grow in the upper 3 feet of most soils. And specifically, themajority of fine roots - those roots that absorb more than 90% of thewater and minerals required for plant growth - usually grow in theupper 12 inches of most soils. In soils that are low in soil oxygen -compacted clayey soils or water-soaked soils - all roots may beconfined to the upper few inches, rarely penetrating deeper than acouple of feet.

When the roots of trees and shrubs are buried too deep, their healthand condition are often affected over time, and sometimesimmediately. Health refers to their growth rate, leaf color, ability torecover from diseases and damage, and ability to withstand our harshwinters. Condition refers to their structural integrity: sound stemwood that is free of decay, cracks or weak points; supportive rootsystems, and canopies that are free of large amounts of dead wood.

A properly planted or established tree or shrub normally will have theroot collar flare at or slightly below the soil or mulch level. The rootcollar flare is the transition area between stem wood and the first,main order roots. In natural plantings, the root collar flare is clearlyvisible above the soil line, or may be slightly covered by leaf litter.When root systems are buried, less soil oxygen and water is availableto the roots, and the roots must grow closer to the surface wherethere usually is a more reliable source of both. The energy that anewly transplanted tree or shrub must use to grow new roots anddevelop a normal, expanded root system must be used to growupward before it can grow in a normal outward direction.

Some, maybe many plants survive this burial and live normal livesafter developing a normal root system. Others begin a long, slowdecline of health and condition, and either die prematurely or failsuddenly during wind or ice storms. Often these plants die ofsecondary problems, not directly related to the dysfunctional rootsystem. If root systems are abnormal, the health of the plant isstressed or strained to a point that the plant becomes abnormallyvulnerable to common site stresses. Whereas healthy plants cansurvive most periodic droughts or defoliation due to insects, stressedplants may die from the additional stresses placed on them.

Research conducted in the Forest Resources Department at theUniversity of Minnesota has revealed that buried root systems ofstreet trees is alarmingly common. In two randomized studies, it wasfound that the main order roots of sugar maples, green ash, andlindens were buried with 1-11 inches of soil (total number sampledwas 302). When the trees were then condition rated (a numericalevaluation of the condition of the stems, canopies and foliage), therewas a direct relationship between declining tree condition and depth of



soil over the roots. In other words, as main order roots were coveredby more and more inches of soil, the condition of all three treespecies further declined.

In addition to the decline in health and condition of trees, burying rootcollar flares may create another adverse condition. As root collar flaresare increasingly buried, more of the stem tissue is buried and out ofsight. A condition termed stem-girdling roots often develops in thisstem-buried situation. Roots that have grown up toward the soilsurface often wrap around or run close to the buried stems. As theseroots enlarge over the years, along with the normal enlargement ofthe buried stems, the roots begin to compress and weaken the stemtissues. This creates a weak point in the tree's stem and leaves thetree more vulnerable to stem breakage during windstorms. Also, thereis a general decline in the remaining root system. The compressionmakes it more difficult for the roots to move water and minerals up tothe foliage, and more difficult for the tree to move photosynthates("food") to the roots. Over time, the root system declines in healthand the aboveground canopy and foliage likewise declines.

How deep is too deep? Based on the previous studies, as little as oneinch of soil over the root collar flare can disguise stem-girdling rootsuntil it is too late. With sugar maple in particular, the significantdecline in health began when the soil depth was 4 inches. Regardless,there is no biological reason to bury root collar flares. Healthy treesgrowing in native forests have visible root collar flares at the soil line.Therefore, it is not logical to believe that planting deeper is better.

To prevent early decline or sudden failure during windstorms, makesure that those first, main order roots that originate at or near the soilline are planted at that depth in the landscape. Make certain thatthose roots are at the top of the soil ball of balled-in-burlap trees andcontainerized trees before you dig the planting hole. Either dig downthrough the top of the soil ball with a trowel until you find those firstroots, or probe down with a stiff wire to find the depth of soil over theroots. If there are 4 inches of soil over the roots of the purchasedplants, dig the hole 4 inches shallow and scrape off the excess soilbefore mulching the newly planted tree or shrub. These few minutesof care at planting time will help ensure that you enjoy a healthy,longlived landscape tree or shrub.



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It Might Be Worth SavingTransplanting Trees and ShrubsPart I: Preparing for the Move"I don't know anything about planting trees, but my neighbortold me that you shouldn't plant in the autumn in Minnesota.""I was at the local nursery last weekend and they had signsadvertising "Fall is for Planting"." Who should you believe?

Part of this contradiction involves mythical information vs. factualinformation. A bigger part of the contradiction relates to thedifferences between planting and transplanting. Most of the mythicalinformation revolving around the blanket statement "you shouldn'tplant in the autumn in Minnesota" is a misunderstanding. Planting isliterally placing a plant in the ground at its (hopefully) permanentgrowing site. Transplanting involves digging a plant from one site andtransferring the tree or shrub to a new site. When planting is done,theoretically, no roots are lost. When transplanting is done themajority of the tree or shrub's original root system is cut off duringthe process.

It's SHOCKING! The loss of roots during the transplanting procedurenormally induces a health condition called transplant shock. Thiscondition is actually less ominous than the term implies, and the vastmajority of transplanted trees and shrubs fully recover in a relativelyshort amount of time. During this shock period, however, theabbreviated root system must recover and reestablish a morecharacteristic "root:shoot" balance. During this recovery period thetree or shrub exhibits retarded growth above ground (contrary towhat's going on below ground), maybe a little branch or twig diebackand often less and smaller leaf production.

As the tree or shrub is growing through this recovery period, it's morevulnerable to stressful weather and landscape conditions that healthyplants would normally be able to tolerate. Short-term drought, hotand windy weather, and early, deep freezes can result in someabnormal damage to the plants. Whether the plant is a native one oran introduced one, they're all vulnerable to transplant shock.

When the leaves are falling, the roots are growing. Autumn, especiallyearly through mid-autumn, is actually an excellent time to transplantmany trees and shrubs in Minnesota because of the aggressive rootgrowth going on below ground. Normally, the autumn soiltemperatures and moisture content in most Minnesota landscapes areideal for root growth. That's why most field nurseries "root-prune"trees and shrubs in the weeks during late summer to early autumn.

Warm soil temperatures + uniform soil moisture = new roots.

Spring is also an excellent time period for transplanting, especially if itcan be done after the ground thaws and the leaves emerge. Both



spring and autumn seasons present the advantage of moving largelydormant plants, and the disadvantage of not knowing what thefollowing months will be like (weather-wise). Droughty, hot and windysummers can be just as stressful on newly transplanted trees andshrubs as early, windy, bitterly cold and long winters.

Why take the chance and potentially waste all the efforts oftransplanting something when it's easier to just buy a new tree orshrub? Good question!

Maybe the plant has some sentimental value, such as a memorialtree or a shrub that you propagated from your grandparent'sgarden?…GOOD REASON!

Maybe the tree has some historical significance, and is worthpreserving, such as the "Eagan Oak" that was transplanted in2001?…GOOD REASON!

Maybe it's a unique species, or a species that isn't normally foundgrowing in Minnesota, such as the Japanese maple in GrandMarais, or a topiary juniper that has taken you years to develop?…GOOD REASON!

Maybe it's just a beautiful specimen, the most perfect potentillayou've ever seen?…GOOD REASON!

Maybe the tree or shrub is in pretty bad shape, unhealthy,unshapely, and a new site could improve its appearance?…BADREASON!

As a rule of thumb, if the plant is in poor health or poor condition, itprobably would be best to transplant it to the chipper and then to themulch pile. You can do this during any season.

Okay, you've convinced me. Can I move anything, spring or fall? Well,yes, you can move anything, but it may not survive! Literally, justabout any tree or shrub can be moved, but there are definite limits tosuccess (a.k.a., the plant actually lives).

Smaller trees and shrubs transplant more successfully. They'reyounger and recover from the transplant shock much sooner andeasier. Plus, there's a better chance that you will be able totransplant a larger percentage of the roots if the plant is smaller. Forinstance:

Root and Top Growth of a One-Inch Caliper Tree FollowingTransplanting (Reyes, 2002)A 1" caliper tree would have a root diameter of 4.5 feet. By nurserystandards a root ball of about 1.5 feet would be moved. Less than 5%of the root system is transplanted.

First YearThe tree is under severe water stress soon after transplanting. Withgood care the stress diminishes, and the root system diameter shouldincrease to 4.5 feet (100% of the original) by the end of the first year.Roots and top are now balanced and the tree should grow normally.

Root and Top Growth of a Four-Inch Caliper Tree Following Transplanting



A 4" caliper tree would have a root diameter of 18 feet. A root ball of3.5 feet would be moved. Less than 5% of the root system istransplanted in the root ball.

First Year Root system diameter increases to 6 feet, 9% of original volume. Withless than 10% of the absorbing roots to support a full crown (top),the tree is often under severe water stress, inhibiting top growth,including bud formation.

Second YearRoot system increases to 9 feet, 23% of original volume. The tree isfrequently under water stress, inhibiting current season growth.

Third YearRoot system diameter increases to 12 feet, 41% of original volume.As root/top balance is gradually restored, the tree is exposed to lesswater stress and growth improves.

Fourth YearRoot system diameter increases to 15 feet, 60% of original volume.The effective rate of root generation accelerates as the overalldiameter of the root system increases.

Fifth YearRoot system diameter increases to 18 feet, 100% of original volume.Roots and crown and the tree should grow normally.

Healthy plants transplant more successfully. It takes a lot of theplants stored energy to establish a new, more characteristic root



system. If a plant is unhealthy, it probably has a very poor, energyreserve system. Not only will it be more difficult for this plant torecover its root system from the shock of transplanting; the energydrain could push this tree or shrub over the edge from unhealthy todead.

How do you know if it's healthy? If the foliage is undersized for thespecies, it may not be healthy. If the canopy (branches with leaves) issparse for the species, it probably isn't very healthy. If there is a lotof branch dieback, it's probably not healthy. If there is decay in thestem/s, infestations of boring insects and/or infectious diseases of thestem or leaves…transplant it to the chipper.

SOME plant species just do better if moved in the spring:

Carpinus Acer rubrum Berberis

Magnolia Betula Cotoneaster

Populus Cornus Ilex

Quercus (most species) Prunus Pinus

Chamaecyparis Pyrus Rhododendron

Crataegus Salix Taxus

Tilia tomentosa Tsuga

Viburnum

Stick with Spring Spring best, Autumn w/care Early Autumn

How can I improve the chances of a successful transplant?

Build up the health of the plant before the move. If you're planningon moving the plant in the spring, start with the health program thepreceding autumn or summer. If it's nutrientstressed, fertilize it. Don'tallow it to become water-stressed… keep the soil uniformly moist.Control any insect pests or diseases. Prune out any dead wood and/orweakly attached branches. Mulch as much of the root zone as you canstand. This gets rid of grass competition, lessens the need forconstant watering, and keeps the soil warmer into late autumn (forbest root growth).

Root prune the plant, at least one season (spring or autumn) beforethe move. Root pruning woody plants encourages a more compact anddense root system. Therefore, when you finally move it, the tree orshrub will have a higher percentage of its most important rootscontained within a smaller soil volume.

As a rule of thumb, for each inch of stem caliper, root prune at adistance of 10-12 inches out from the stem of the plant. For instance,if the tree has a one-inch stem caliper, the diameter of the root-pruned area would be 20-24 inches. Simply determine the appropriatedistance from the stem, draw a circle around the stem with thisdistance as the radius, and sink the blade of your digging spade downas deep as you can go all the way around this circle. This one practice



will dramatically reduce the transplant shock on the plant when it isfinally transplanted the following season or year.

You've sold me on the idea of transplanting, but the tree isjust too big for me to move it. Are there companies thatspecialize in transplanting large trees and shrubs?

Yup. There are several companies in Minnesota that specialize intransplanting large plants with various sizes of tree spades. However,these companies are busy, and it would be smart to includecontacting them at least one season before the transplant date.

A Partial Listing of Companies That Transplant Large Trees andShrubs:

Minnesota Valley Landscape 952-445-4004

Halla Nursery 952-445-6555

Bob Matiski Tree Moving 651-436-1709

Witzel Tree Moving 651-459-4581, 651-769-1759

Strese's Tree Service 507-645-6137; cell 612-282-3526

References cited:Reyes, Jonah. 2002. Arboriculture Myth Exposed: Bigger is Better? Tree CareAdvisor

Even small trees suffer from winddamage. This small hackberry with abroken leader and branches is notworth the time and effort it takes tomove a tree.

The hackberry pictured here is worthmoving. A good dominant leader anda decent branching habit makes it alikely candidate.

Pruned root stubs with a summers re-growth



Malus spp. “Spring Snow” root stock Fraxinus pennsylvanica “Green Ash”root stock

Root Pruning encourages a more compact and dense root system.Therefore, when you finally move it, the tree or shrub will have ahigher percentage of its most important roots contained within asmaller soil volume.

Step 1: Measure the trunk diameter Step 2: For every inch of Trunkdiameter - measure out from thestem 10-12 inches and use thatdistance as the radius to trace acircle around the tree

Step 3: Using a 12-18 inch spade -Follow the outline and fully insert thespade, completely encircling the tree.



Root pruning complete.



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It Might Be Worth SavingTransplanting Trees and Shrubs Part II: Making the MoveWeeks or months have now passed since you made the decision tomove the tree or shrub and hopefully prepared that plant for thejourney. I'm sure that to some people, all of this planning seems a bitexcessive. If all you are doing is moving a 24 inch Potentilla, I'd haveto agree with you. Just dig it up and move it anyway you can…it WILLlive. However, since of lot of other readers may be thinking aboutmoving a 12 foot spruce, or 20 year old lilacs or a 5 inch caliperbasswood, the excessive planning is much more necessary.

Figure 1: Green Ash - Pot-in-Potcontainer study. Root Pruned prior togrowing season

After four months in a container.

A lot has been happening below ground since you root-pruned thattree or shrub a few weeks or months ago, but unless you have x-rayvision it hasn't been obvious. Every root that you cut during thatprocess has rewarded you ten-fold…at least. The two photographs inFigure 1 show the effect of timely root pruning. The image to the leftis of a green ash, immediately after root pruning. The image below isthe same tree, four months later. The net result is not only a muchmore extensive root system, but one that is contained in a muchsmaller area. This visually exhibits why root-pruned plants survivetransplanting so much better than those not pruned.

Before you transplant, take a look up, around and beneath. It'simpossible to avoid talking about tree or shrub placement in atransplanting primer. After all, the plant is theoretically being movedto a "better" site than before. Add these next steps to your checklist:

1. Look up. Don't plant in a site where the mature tree or shrubcan interfere with utility lines or views from windows. Anddon't fool yourself by thinking that regular pruning can keepthe plant size in check. Too much work, too hard on the plant,too easy to forget.

2. Look around. Will the new placement create a blocked sightline? For instance, as it matures, will it block the view of thestreet from your driveway as you back out? Or the clear viewat an intersection of streets? If so, don't plant it there. If theproposed planting site is within 60 of the street, the street is abusy street and you know from past experience that a lot ofdeicing salt is used, don't plant the tree or shrub there unlessit's known to be tolerant of Minnesota's main source ofpollution. For a list of trees and their tolerances to deicing saltexposure, refer to "Minimizing De- Icing Salt Injury to Trees,"(Johnson, Sucoff, 1995). If the plant could get so broad that itwould interfere with pedestrians walking by or lawnmaintenance, don't plant it there thinking that pruning wouldcontain the problem.

3. Look down. Actually, have Gopher State One Call look downand deep for you. I should have mentioned this in part I before



you rootpruned, and hopefully none of you severed anyutilities. Definitely contact them now at: 651-454-8388, or 800-252-1166, or www.gopherstateonecall.org. It seems like a bitof an annoyance, but it's cheap insurance.

While you're looking down, check the soil for compaction ordrainage problems. If you can dig two spades lengths deepinto the soil, you don't have a compaction problem. If you needto jump up and down on the shovel and have your 300 poundneighbor do it, too…you have a compaction problem.Compaction problems can be alleviated somewhat by anextensive site preparation (e.g., loosening the soil in an area10 feet in diameter), and it's so much easier to do that beforeyou move the new tree or shrub. Poor drainage is anotherstory, though.

To check for drainage, dig or auger a hole 24 inches deep. Fillwith water and allow it to completely drain. Fill a second time.That second filling should be drained within 24 hours. If it isn't,drainage may be an issue. If the transplanted tree is a sugarmaple…it's an issue. If it's a silver maple, it probably isn't.Correcting soil drainage problems is difficult and oftenexpensive. Your best move is to avoid them if they couldbecome problematic for tree or shrub health.

Might as well have that soil tested, too. The most critical thingto determine is the soil pH (whether it's acidic or alkaline), anddon't think that just because the native soils are acidic thatyour soil will be acidic. Most "urbanized" soils are alkaline,some just slightly and others obscenely. If the soil pH is 7.5 orso, and the transplanted tree is a river birch…don't plant itthere! It WILL decline and die prematurely. And as with poordrainage, soil alkalinity is difficult and expensive to change.

I'm ready to transplant the tree but it's autumn now. Should Iwait until spring?

In Part I, I hinted that time of year may be more of a perceivedproblem, rather than a real problem. Certainly, there are some plantsthat are best and most successfully moved in the spring (see Part Ifor a partial listing), but quite honestly, there's little documentedresearch that success or failure rates differ dramatically by seasons(obvious exceptions would be mid-winter and mid-summer).

Most of you reading this live in the southeastern part of Minnesota.That's just a demographic fact, not a location prejudice. Upstate NewYork is very similar climate-wise to much of Minnesota, especially thesoutheastern part of Minnesota. In a documented, two-year researchexperiment conducted by Cornell University in upstate New York(Buckstrup and Bassuk, 2000), hackberry (Celtis occidentalis),ironwood (Ostrya virginiana) and bicolor oak (Quercus bicolor)survived and grew just as well when transplanted in the autumn asthey did in the spring. Sometimes better in the autumn. That'sresearch-based information. It's not inclusive for every tree or shrubimaginable, but it is factual and more reliable than memory or "myneighbor said" information.

What ARE the most important factors for transplant success?



Transplant as many roots as possible.

Never let them dry out.

Prepare the new site for root growth.

Plant the tree or shrub at the right depth.

Take care of the plant after the move, for the life of the plant(figuratively and literally).

Transplant as many roots as possible If you root-pruned the tree or shrub at least one season before themove, the plant now has a much more concentrated root system in amore confined area. This means that you will be able to move a muchmore extensive root system. The way it is moved depends on speciesand size.

Bare-root transplanting is just as the term implies: moving the plant'sroot system with little to no soil attached. Whenever possible, this isthe preferred method because it is relatively simple, the (lighter) plantis easier to handle and move, any root problems become obvious andeasier to correct, and in fact, you can usually move a larger rootsystem this way. It is not usually recommended for movingconifers or trees larger than 2 inches in caliper (but those rules can bebent).

Digging Bare-root

Bare-root stock

1. If possible, dig down a few inches beyond that rootpruningtrench that you dug a season ago. You will hit some newroots, but the majority of the roots will be contained within thediameter of the root-pruned area. As you are digging down,pry the shovel to lift the roots and loosen the soil.

2. Loosen the soil within the diameter of the new trench. If thesoil is very dry, it sometimes helps to moisten it a few inchesdeep the day before you dig. My implement of choice forloosening the soil is a "potato fork," which is similar to a shortpitchfork with broad and flat tines. Loosening the soil is walkinga fine line between freeing the roots and cutting them. Youdon't want to cut all the roots off, just loosen the soil fromthem so the plant can be lifted.

3. If there are any roots growing down, slip under the root masswith your shovel or use a loppers to cut those roots. Now theplant should be free from the growing site and you can shakemost of the remaining soil off.

4. Keep the roots moist. Immediately after freeing the plant fromthe soil, "heel" it back in with loose soil and moisten it. Analternative would be to cover the roots with wet straw orwoodchips and cover with a tarp or plastic. Those roots can diein minutes when exposed to air.

Now, I've left a couple "holes" that need filling.

Caliper. This is the thickness of the stem, which is measuredapproximately 6 inches above the ground line. However, if thestem measurement taken at that point is greater than 4 inches



thick, move up the stem another 6 inches and record the stemthickness at that point.

Diameter of root mass. The American Association of Nurserymenhas developed the "American Standard for Nursery Stock."(reference and address in concluding reference section). Accordingto the standards, a tree with a 1 inch caliper should have a 18inch diameter bare root system…AS A MINIMUM. A 2 inch calipertree should have a 28 inch diameter bare root system… AS AMINIMUM. For a 3 inch caliper tree, at least 38 inches. For a 3 foottall shrub, 14 inches in diameter; 16 inches for a 4 foot shrub; 18inches for a 5 foot shrub; and 20 inches for a 6 foot shrub.

Keep in mind that these are MINIMUM dimensions. The more rootsyou transplant with the tree or shrub, the more successful themove will be.

Ball and Burlap

Balling and burlapping (B&B) the root system requires much moreskill, patience and muscles! For those larger trees and/or conifers thattraditionally move better with a soil ball surrounding the roots, thisand moving the plants with a tree spade (mechanical digger) are thepreferred methods. The irony of it is that the root system is actuallysmaller (according to the Standards) for B&B dug versus bare-rootdug plants. For instance: 2 inch caliper B&B should have a minimumsoil ball diameter of 24 inches (compared to 28 for bare-rooted).

If you decide to ball and burlap the plant, the process is a bitdifferent.

Foliage and branches tied up

1. Again, if the soil is dry, moisten it to a depth of several inches theday before the move. Carefully scrape away all excess surface soiluntil you find the first branch root/s. This should be the very topof your soil ball when the plant is finally dug.

2. Use a flat spade, similar to a "sod-cutting" spade, instead of arounded or "spoon" shovel. Turn the face of the shovel away fromthe stem of the plant as you dig down around the minimum rootball diameter.

3. As you sink the spade into the soil and cut the roots, press thehandle back toward the stem and scoop the soil out away fromthe soil ball. This is the opposite action taken when bare-rooting aplant. This action compacts the soil into a solid root/soil ball with



Compacting and removing soil.

each spade of soil scooped away.

4. After the first "lap" around the root ball diameter, begin a secondlap digging down deeper. In effect, you will be digging this trencharound the soil ball two spade-lengths deep.

Shave and taper the ball.

5. Begin "shaving off" soil from the soil ball. Don't try to move a soilball if there are no roots to hold it intact, because it won't stayintact! Shave off soil until you hit enough roots that you can beconfident that it will hold together. Then, begin cutting down andinto the bottom center of the soil ball. This is known as "tapering"the soil ball, and again, if you don't hit any roots, don't try tomove that soil with the soil ball. Keep tapering in until you begincutting roots.

Burlapping

6. Once the soil ball is shaved and tapered, fold up a sheet of burlapor an old sheet, slip it down into the hole against one side of thesoil ball and roll the soil ball back onto the burlap or sheet. Pullhalf of the burlap or sheet under the soil ball and up around theopposite side.

Tied up and ready to move

7. Pull up the four corners of the burlap or sheet, tie them to eachother and snug up the wrapping. Sometimes it is necessary to"bind up" the burlap or sheet with twine or a rope to hold it alltogether.

8. Get some help and lift the plant out of the hole.

That sounds like a lot of work and very confusing! You're right!

It took me about four months to learn how to ball and burlapprofessionally when I started working for a nursery as a college



student. It's very hard work, frustrating at times, and every tree andshrub is a bit different. I'd recommend that you hire someoneexperienced at this art if it needs to be done, or have it moved with atree spade.

The move As mentioned earlier, if the soil is compacted, loosen it as much asyou can tolerate. Then pass the shovel or roto tiller off to someoneelse and have them loosen it as much as they can tolerate. This willpay off in the form of a shorter transplant shock period and ahealthier, longer-lived tree or shrub.

Replanting the shocked tree or shrub is at least as important as thedigging process. For detailed information on the best plantingpractices, refer to "Planting Trees and Shrubs for Long-Term Health,"which is listed in the concluding reference section. The steps aresimple, however.

Measure the soil ball

1. Measure the depth of the root system if it's barerooted, or the soilball depth if it's B&B or tree spade dug.

determine depth

2. That measured depth is the deepest that the new planting holeshould be. If you are to err, err on the side of planting high. Thisdoesn't mean that the roots will be sticking up out of the ground.You will just need to haul in more good soil to cover those higherroots, creating a planting berm.

3. The width of the hole depends on the nature of the soil, thecompacted nature to be specific. If the new planting site hasbeautiful, loose soil, the width of the planting hole is not a bigissue. It should be large enough to place the soil ball/roots into itand work the backfill soil in around those roots. If the soil is verycompacted, then the wider the planting hole, the better.

4. Double-check that planting depth and make sure those firstbranch roots are no deeper than the landscape surface. Don'tworry, they're not going to die; they will end up with a lightdressing of mulch over them.



Double check depth of 1st branchroots

5. If the tree or shrub has been balled and burlapped, backfill abouthalf way up the soil ball depth and then cut off the remainingburlap or sheet above that point.

6. Complete the backfilling, water the soil ball/root area thoroughlyand mulch the planting site with 2-4 inches of the mulch of yourchoice. Don't pile ANY mulch up against the stem, however.

7. Religiously water, sometimes every day depending on the season,soil drainage and size of the transplant. Allow the soil to drainafter each irrigation, but never allow the roots and the soil aroundthe roots to completely dry out

8. Don't prune off branches to compensate for root loss! Thispractice may seem logical, but it's not bio-logical. If branchessubsequently die, then prune them off.

There is a "magic bullet!" Everyone wants to know what they cando to ensure transplant success. Is it fertilizer? No. Is it soil fungi orbacteria? No. Is it cow manure, peat moss, composted leaves? No. It'swater. Not too much, not too little, not once a week, not one inch ofwater per week, not just before planting, not only after planting. It'sthe amount needed to keep the roots moist from the time you begindigging until the tree or shrub is safely beyond transplant shock (atleast one year). And then after that, for the life of the tree. Whenwater is maintained at an optimum level, then fertilizers, soilamendments, microbial inoculations may be beneficial. If water islacking or excessive, those other amendments are either worthless ordamaging to plant health.

Occasionally, trees may need some support via stakes for a shortperiod of time after transplanting. For more information on stakingand guying trees, refer to the Forest Resources Extension web sitelisted in the reference section. Often, trees and shrubs need somewinter protection from hungry critters. Again, refer to the ForestResources Extension web site.

References

American Association of Nurserymen. American Standard for NurseryStock, ANSI Z60.1. 1250 I Street, N.W., Suite 500, Washington, D.C.20005.

Buckstrup, Michelle J. and Nina L. Bassuk. 2000. TransplantingSuccess of Balledand- Burlapped Versus Bare-Root Trees in the UrbanLandscape. Journal of Arboriculture, 26(6): November, 2000. P. 298-308.



Hargrave, Rebecca, Gary Johnson and Michael Zins. 2002. PlantingTrees and Shrubs for Long-Term Health. University of MinnesotaExtension Service, MI- 07681. 13 pages.

Johnson, G.R. and Ed Sucoff. 1995. Minimizing De-Icing Salt Injury toTrees. University of Minnesota Extension Service, FO-1413, 7 pages.

Forest Resources Extension, University of Minnesota. Click on TreeHealth. (view forest website)

Minimizing De-Icing Salt Injury to Trees (view minimizing website)

Rodent Damage. Click on Trees - Rodent Damage (view forest website)

Urban and Community Forestry. Click on Urban and CommunityForestry (view forest/urban website)

Planting. Click on Planting (view forest/planting website)

Staking and Guying. Click on Staking and Guying (view forest/staking website)



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Pruning Trees and ShrubsMike Zins and Deborah Brown, Extension Horticulturalists

FO-00628 Revised 1997

Pruning is a horticultural practice that alters the form and growth of aplant. Based on aesthetics and science, pruning can also beconsidered preventive maintenance. Many problems may be preventedby pruning correctly during formative years for a tree or shrub.

REASONS FOR PRUNING

1. Prune to promote plant health Remove dead or dying branches injured by disease, severeinsect infestation, animals, storms, or other adversemechanical damage.

Remove branches and branch stubs that rub together.

Avoid topping trees. Removing large branches leaves stubs thatcan cause several health problems. It also destroys the plant’snatural shape and promotes suckering and development of weakbranch structure.

2. Prune to maintain plants; intended purposes in alandscape, such as:

encouraging flower and fruit development,

maintaining a dense hedge, or

maintaining a desired tree form or special garden forms.

3. Prune to improve plant appearanceAppearance in the landscape is essential to a plant’s usefulness.For most landscapes, a plant’s natural form is best. Avoidshearing shrubs into tight geometrical forms that can adverselyaffect flowering. Alter a plant’s natural form only if it needs to beconfined or trained for a specific purpose. When plants are prunedwell, it is difficult to see that they have been pruned! Prune to:

control plant size,

keep evergreens well-proportioned, or

remove unwanted branches, waterspouts, suckers, andundesirable fruiting structures that detract from plantappearance.

4. Prune to protect people and property.Remove dead branches.

Have hazardous trees taken down o Prune out weak ornarrow-angled tree branches that overhang homes, parkingareas, and sidewalks — anyplace falling limbs could injurepeople or damage property.

Eliminate branches Eliminate branches that interfere withstreet lights, traffic signals, and overhead wires. REMEMBER,DO NOT attempt to prune near electrical and utility wires.



Contact utility companies or city maintenance workers tohandle it.

Prune branches that obscure vision at intersections.

For security purposes, prune shrubs or tree branches thatobscure the entry to your home.

Figure 1. Prune this young tree toremove

PRUNING BEGINS AT PLANTING TIME

receive. It is critical for young trees to be trained to encourage themto develop a strong structure. (See Figure 1)

Too many young trees are pruned improperly or not pruned at all forseveral years. By then it may become a major operation to removebigger branches, and trees may become deformed.

At planting, remove only diseased, dead, or broken branches. Begintraining a plant during the dormant season following planting.

Prune to shape young trees, but don’t cut back the leader.

Remove crossing branches and branches that grow back towardsthe center of the tree.

As young trees grow, remove lower branches gradually to raise thecrown, and remove branches that are too closely spaced on thetrunk.

Remove multiple leaders on evergreens and other trees where asingle leader is desirable Pruning young shrubs is not as critical aspruning young trees, but take care to use the same principles toencourage good branch structure.

When planting bare root deciduous shrubs, thin out branches forgood spacing and prune out any broken, diseased, orcrossing/circling roots.

When planting bare root deciduous shrubs for hedges, prune eachplant to within 6 inches of the ground.

Newly planted shrubs require little pruning if they were container-grown or were dug with a soil ball.

PRUNING LARGE ESTABLISHED TREES

Leave the pruning of large trees to qualified tree care professionalswho have the proper equipment. Consider the natural form of largetrees whenever possible. Most hardwood trees have rounded crownsthat lack a strong leader, and such trees may have many lateralbranches.

The three most common types of tree pruning are:

1. Crown Thinning-selectively removing branches on youngtrees throughout the crown. This promotes better form andhealth by increasing light penetration and air movement.Strong emphasis is on removing weak branches. (Don’t overdoit on mature trees.)

2. Crown Raising — removing lower branches on developing ormature trees to allow more clearance above lawns, sidewalks,streets, etc.



3. Crown Reduction — removing larger branches at the top ofthe tree to reduce its height. When done properly, crownreduction pruning is different from topping because branchesare removed immediately above lateral branches, leaving nostubs. Crown reduction is the least desirable pruning practice.It should be done only when absolutely necessary.

Pruning small branches

PROPER BRANCH PRUNING

To shorten a branch or twig, cut it back to a side branch or makethe cut about 1/4 inch above the bud.

Always prune above a bud facing the outside of a plant to forcethe new branch to grow in that direction.

Pruning large braches

To remove large branches, three or four cuts will be necessary toavoid tearing the bark. Make the first cut on the underside of thebranch about 18 inches from the trunk. Undercut one-third to one-half way through the branch. Make the second cut an inch furtherout on the branch; cut until the branch breaks free.

Before making the final cut severing a branch from the main stem,identify the branch collar. The branch collar grows from the stemtissue around the base of the branch. Make pruning cuts so thatonly branch tissue (wood on the branch side of the collar) isremoved. Be careful to prune just beyond the branch collar, butDON’T leave a stub. If the branch collar is left intact after pruning,the wound will seal more effectively and stem tissue probably willnot decay.

The third cut may be made by cutting down through the branch,severing it. If, during removal, there is a possibility of tearing thebark on the branch underside, make an undercut first and thensaw through the branch.

Research has shown wound dressing is not normally needed onpruning cuts. However, if wounds need to be covered to preventinsect transmission of certain diseases such as oak wilt, use latexrather than oil-based paint.

TIMING

The late dormant season is best for most pruning. Pruning inlate winter, just before spring growth starts, leaves fresh woundsexposed for only a short length of time before new growth begins thewound sealing process. Another advantage of dormant pruning is thatit’s easier to make pruning decisions without leaves obscuring plantbranch structure. Pruning at the proper time can avoid certain diseaseand physiological problems:

Pruning at the proper time can avoid certain disease and physiologicalproblems:



To avoid oak wilt disease DO NOT prune oaks during April, May, orJune. If oaks are wounded or must be pruned during thesemonths, apply wound dressing to mask the odor of freshly cutwood so the beetles that spread oak wilt will not be attracted tothe trees.

To avoid increased likelihood of stem cankers, prune honeylocustswhen they are still dormant in late winter. If they must be prunedin summer, avoid rainy or humid weather conditions.

Prune apple trees, including flowering crabapples, mountainash,hawthorns and shrub cotoneasters in late winter (February-earlyApril). Spring or summer pruning increases chances forinfection and spread of the bacterial disease fireblight. Autumn orearly winter pruning is more likely to result in drying and die-backat pruning sites. o Some trees have free-flowing sap that “bleeds”after late winter or early spring pruning. Though this bleedingcauses little harm, it may still be a source of concern. To preventbleeding, you could prune the following trees after their leaves arefully expanded in late spring or early summer. Never remove morethan 1/4 of the live foliage.

Examples include:all maples, including boxelder

butternut and walnut

birch and its relatives, ironwood and blue beech.

Trees and shrubs that bloom early in the growing season on lastyear’s growth should be pruned immediately after they finishblooming:

Apricot clove currant Juneberry

Azalea flowering plum lilac

Chokeberry cherry magnolia

Chokecherry forsythia early blooming spirea

Shrubs grown primarily for their foliage rather than showy flowersshould be pruned in spring, before growth begins:

alpine currant dogwood purpleleaf sandcherry

Barberry honeysuckle smokebush

Buffaloberry ninebark sumac

burning bush peashrub

Shrubs that bloom on new growth may be pruned in spring beforegrowth begins. Plants with marginally hardy stems such as clematisand shrub roses should be pruned back to live wood. Hardier shrubssuch as late blooming spireas and smooth (snowball) hydrangeasshould be pruned to the first pair of buds above the ground.

PRUNING HEDGES

After the initial pruning at planting, hedges need to be pruned often.Once the hedge reaches the desired height, prune new growth backwhenever it grows another 6 to 8 inches. Prune to within 2 inches ofthe last pruning. Hedges may be pruned twice a year, in spring and



again in mid-summer, to keep them dense and attractive. Prunehedges so they’re wider at the base than at the top, to allow all partsto receive sunlight and prevent legginess.

RENEWAL PRUNING FOR OLDER OR OVERGROWN SHRUBS

Every year remove up to one-third of the oldest, thickest stems ortrunks, taking them right down to the ground. This will encourage thegrowth of new stems from the roots. Once there are no longer anythick, overgrown trunks left, switch to standard pruning as needed.

PRUNING EVERGREENS

With few exceptions, evergreens (conifers) require little pruning.Different types of evergreens should be pruned according to theirvaried growth habits.

Spruces, firs and douglas-firsdon’t grow continuously, but canbe pruned any time because they have lateral (side) buds that willsprout if the terminal (tip) buds are removed. It’s probably best toprune them in late winter, before growth begins. Some springpruning, however, is not harmful.

Pines only put on a single flush of tip growth each spring andthen stop growing. Prune before these “candles” of new needlesbecome mature. Pines do not have lateral buds, so removingterminal buds will take away new growing points for that branch.Eventually, this will leave dead stubs. Pines seldom need pruning,but if you want to promote more dense growth, remove up to two-thirds of the length of newly expanded candles. Don’t prunefurther back than the current year’s growth.

Arborvitae, junipers, yews, and hemlocks grow continuouslythroughout the growing season. They can be pruned any timethrough the middle of summer. Even though these plants willtolerate heavy shearing, their natural form is usually mostdesirable, so prune only to correct growth defects.

USE THE RIGHT TOOLS FOR PRUNING

The right tools make pruning easier and help you do a good job.Keeping tools well-maintained and sharp will improve theirperformance. There are many tools for pruning, but the following willprobably suffice for most applications:

Pruning shears

A good pair of pruning shears is probably one of the mostimportant tools. Cuts up to 3/4 inches in diameter may be madewith them.

Lopping shears are similar to pruning shears, but their longhandles provide greater leverage needed to cut branches up to11/2 inches in diameter.

Hedge shears are meant only for pruning hedges, nothing else.They usually cut succulent or small stems best.

Hand saws are very important for cutting branches over 1 inch indiameter. Many types of hand saws are available. Special tri-cut orrazor tooth pruning saws cut through larger branches — up to 4inches in diameter — with ease.



Lopping shears

Hedge shears

Hand saws

Pole saws allow for extended reach with a long handle, but theymust be used carefully as it’s difficult to achieve clean cuts withthem.

Small chain saws are available for use on larger branches.Operators must wear protective clothing and exercise caution whenusing them. Never use chain saws to reach above your shoulders,or when you are on a ladder.

Mike Zins and Deborah Brown are Extension Horticulturists with theUniversity of Minnesota Extension Service.

This publication is based on an earlier version written by Mervin Eisel,former Extension Horticulturist.

Produced by Communication and Educational Technology Services,University of Minnesota Extension Service.

Copyright © 2002 Regents of the University of Minnesota. All rightsreserved.

Documents

TCA Reference Manual: Planting Trees