The successful relocation of large trees is both a remarkable and difficult feat. There is definitely an art to it. Tree moving, which allows the addition of mature trees to landscaping projects, has become a popular practice to beautify or otherwise enhance large and small-scale developments.

I have been involved with and have observed many successful tree-moving projects where the relocated trees have contributed significantly to the community for several years now. Some people may, however, have a different opinion.

Tree Relocation Is a Complicated & Risky Prospect

I’ve worked with and read the reports of those who argue that tree relocation is generally a loosing proposition, typically resulting in tree failure. One of these field studies included trees that initially lacked vigor and vitality. Some had experienced heavy fire damage while boxed in the field and most suffered a lapse in care for a period of approximately one year. These circumstances clearly do not provide adequate grounds to arrive at a reasonable conclusion that tree relocation can be dismissed as a means of preserving heritage trees from condemnation due to development.

Although tree relocation is a complicated and risky prospect, it can usually be performed successfully. My experience is that if you start with a healthy tree, box it correctly and at the right time and provide adequate maintenance, you can expect a high rate of success.

There are only a handful of tree moving companies in the United States that are capable of moving large specimen trees with root balls in excess of 10 feet in diameter. I was the staff arborist for one of these companies for six years. During this time, I evaluated trees for their potential to survive relocation, and supervised their care before, during and after. I also made regular site inspections on many projects for up to five years following tree relocation to diagnose problems and to evaluate our tree moving procedures and maintenance practices.

Based on this experience, I will be discussing several topics significant to tree moving in various blog posts. Each of the posts concerning tree moving focuses primarily on the relocation of Quercus agrifolia. I have been involved with many tree relocation projects, both large and small, involving residential, commercial and golf course development and community redevelopment projects.

Conclusion

I have been involved with several projects that include the relocation of Quercus agrifolia in box sizes up to 18 feet. On many of these projects more than 10 years has elapsed since the trees were moved, and they have performed beautifully and continue to show vigor. In more recent years, with greater experience and industry innovations some trees seem to hardly miss a beat when relocated. I attribute these successes to proper selection, preparation, proper pruning, and adequate follow up maintenance.

Tree moving is a big investment and should not be taken lightly. Not only is the relocation process costly, but also long-term maintenance and monitoring must be factored into the budget. There are obviously risks involved with relocation and some trees are poor candidates. In my opinion, tree relocation should be considered as a last resort, it is always best when a tree can remain undisturbed. Tree moving has saved many trees to the benefit of countless communities. Landmark heritage and specimen trees can be spared when it is necessary to make way for development.

The following posts and opinions, therefore, is based on more than six years of observations and hands-on experience working with the relocation of mature trees.

Here are the posts concerning the topic of successful relocation of trees:

Defining a Good Candidate & Box Size

Preparation & Pruning

Fertilization, Supplements & Soils

Cabling / Guy Wires

Planting of Relocated Trees

Maintenance & Irrigation

Pest & Disease Problems

Reestablishment

* These posts were originally published as a full article in Western Arborist Magazine (June 2003). Click here to view the original article in its entirety.

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As stated earlier, my remarks regarding responses to relocation are relevant primarily to Quercus agrifolia. The reestablishment period of relocated trees varies widely among species. Trees reestablish their root to shoot balance by first regenerating root at the expense of shoot growth. Therefore, some trees may have a period of reduced aesthetic quality.

This period can be short providing that the tree was healthy and vigorous initially. My experience is that a minimum of two years or longer is required for reestablishment. This is contingent upon a closely supervised maintenance program. After approximately two years, maintenance demands greatly decrease, reducing tree care costs.

Trees that have been relocated will require some maintenance and monitoring for the remainder of their lives, however requirements continue to diminish as time passes. At the very least, it is recommended that relocated trees be evaluated by an experienced certified arborist no less that 3-4 times a year.

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Root loss associated with tree relocation causes stress, increasing susceptiblity to certain insect and disease pests. Careful monitoring for the signs and symptoms of developing pest problems is needed to prevent or minimize such problems. When dealing with pest problems “the best defense is a good offense”.

It is preferable to prevent problems than to have to deal with them later, hence, careful evaluation and selection, preparation, timing and follow-up care are critical. Some pest and disease issues are best managed by using appropriate chemicals as a prophylaxis. This is especially true in the prevention of bark boring insects.

As mentioned earlier, trees undoubtedly become stressed during relocation; therefore preventative measures must be taken. The most common disease problem encountered in relocated trees is “Phytophthora” , a root and root crown disease of trees associated with poor drainage and over-watering. Although fungicidal treatment may be useful, the best way to manage phytophthora is through careful irrigation practices. Although, other insects and diseases may be noted, only a handful can actually threaten the health and survival of relocated trees. Chemical treatment should be reserved for serious problems.

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These two procedures, I believe, are the most critical factors in the success and survival of relocated trees. Trees are particularly sensitive to soil moisture levels, following the loss of often more than 80 percent of the root system. The need for supplemental water greatly increases due to the reduced capacity of the remaining root system to absorb water. Initially, the root ball soil provides the only reservoir for water until the roots begin to grow into the native soil. Trees that usually survive without water for long periods now require regular and frequent irrigation, resulting in an increased risk of soil pathogens.

A fine balance between soil that is too wet and too dry must be maintained. This can only be achieved by regularly scheduled servicing by experienced staff, usually supervised by a certified arborist. Although the practice of irrigating a tree may sound simple, great care and effort is required to insure proper soil moisture. It is imperative to check soil moisture by using a soil probe before and after watering to determine how much water if any to add. “Monitoring of soil moisture can be scheduled, the actual irrigation cannot”. Two of the most common problems are over or under watering.

In my opinion, the most serious threat to the survival of relocated trees is over-watering. I would rather see irrigation error on the drier side. Over-watering usually occurs when the tree is either planted below grade or the soil grade has been increased around the tree. These conditions frequently result in serious problems. Other conditions that are associated with over-watering include broken irrigation lines, planting in poorly drained soil and at the base of a slope.

Under- watering most often occurs when the irrigation water does not percolate readily into the root ball, this most commonly happens as water runs over the top of the root ball and into the backfill. Consequently, the soil within the root ball remains dry because the water in the backfill does not move readily into the root ball. Soil watering basins must be maintained just inside the edge of the tree root ball to ensure percolation. Mulching, which reduces soil temperature and helps conserve soil moisture, is conducive to new root growth as newly developed fine roots are highly susceptible to desiccation.

One of the key pitfalls related to maintenance is that contractors, developers, homeowner’s etc., rarely budget for post-relocation tree care. Problems requiring immediate corrective action are likely to develop without a maintenance program and regular monitoring. It may be too late by the time someone recognizes the problem. I’ve found that about 70 percent of the failures in relocating trees are attributable to inadequate maintenance. Adverse site conditions, construction-related problems and undetermined causes are responsible for the other failures.

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The planting of relocated trees is fairly straightforward. When working with large trees remember to install guy wires during planting to reduce the risk of the trees toppling. The planting pit dimensions will normally be one to three feet larger than the root ball and up to six inches shallower than root ball depth. Amending the backfill soil is seldom necessary except to correct specific problems determined by a soil analysis.

The compaction of backfill is very important; it not only increases stability but also affects irrigation efficiency by eliminating air pockets. Irrigation water can collect in large air pockets, bypassing the root ball. It is advisable to install a drainage system in all planting pits, with the exception of those where excess water can freely drain away, e.g., sandy soil, slopes or mounds.

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Stabilizing trees during the establishment period to prevent toppling is an extremely important topic when discussing tree relocation , it can determine success or failure. In addition, a falling tree may affect others nearby. Obviously, root anchorage is severely compromised during the boxing process, and for this reason all relocated trees should be guy wired. Typically, one considers installing cables after planting, however, it is equally important to consider stability during boxing, transporting and planting trees.

It is advisable to provide temporary guy wires during these procedures. My experience is that cables must remain in place for no less than two years and in some cases up to five years. Maintenance of cables plays a vital role in the success and safety of tree moving. Proper cable installation and maintenance insures the safety of people, property and the tree as well.

Close up of current years shoot growth, some in excess of 9″.	These two photos are shown in rebuttal to an article published in SCOPE (Santa Clarita organization for planning the community) in 2002, the article can be visited at (www.scope.org/welcome.html). The writer claims that the Quercus lobata is failing due to being moved. The photos I shot were taken in April 2003 of the same exact tree and it is again clear the tree is far from dead.

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I have seen little in the way of fertilizers or supplements that provide a noticeable or significant difference in the survival of relocated trees during the critical period, 30 to 60 days after boxing. I believe, and there is a general consensus within the industry, that fertilization and the use of certain supplements applied during the maintenance phase after this critical period can influence tree performance and long-term survival. Although, I have tried many of the so called,miracle products, I have yet to witnessed a miracle. I have also inoculated several trees using various forms and applications of mycorrhizae, but have not noted any observable change in survival or performance in the treated trees.

I believe that if a tree is healthy prior to relocation, soil nutrient levels are adequate and that the native mycorrhizae are present. However, when a tree is relocated to another site where soil conditions may be unfavorable or nearly sterile due to excavation, loss of topsoil, etc., mycorrhizae and certain amendments may be useful, based on a soil analysis.

According to ISA standards, amending the backfill soil for tree planting is generally not recommended, however, should a soil analysis reveal toxicity or deficiencies, corrective measures are appropriate. When dealing with soils of varying texture and structure, consideration must be given to water percolation, water-holding capacity, drainage and aeration, as irrigation practices may affect survival and performance.

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The maintenance your trees receive is
without question the single most
important aspect in keeping trees healthy.

The team at Arbor Essence can help
keep your trees healthy.

Defining a Good Candidate

The first step in tree relocation is to conduct a comprehensive inspection of the tree and site to determine the likelihood of it surviving and thriving following relocation. The tree must be healthy and vigorous, showing no indications of stress. Structural integrity is also critical because many trees are relocated from oak woodlands to areas of high traffic where hazard potential is a definite concern.

Trees must be thoroughly inspected for the signs and symptoms of significant insect pests and diseases. Look for structural problems, e.g., included bark, girdling roots, cracks, cavities and decay in the trunk and branches. Tree species must also be considered, as there are several that do not respond well to relocation.

Arbutus unedo- This tree was relocated approximately 5 years ago. It was put into a 20′ box. The tree continues to perform and is clearly an asset to the property.

Box Size

Determining the adequate box size for a particular tree requires a great deal of experience and knowledge. Considerations include, but are not limited to, species, trunk diameter, canopy size, structure, size of roots and, of course, site conditions. The ISA standard for determining container size is approximately nine inches (diameter) of root ball to each inch of trunk diameter. Most tree companies, however, allow only about seven inches of root ball per inch of trunk diameter.

To be competitive, tree-moving companies are forced to take this to the extreme by putting trees in comparatively small boxes. While some tree species may survive with smaller root balls than recommended, others species are very sensitive to box size. On the more sensitive species, I recommend using the largest box allowable considering the project budget. The greater the root mass the greater the likelihood of success.

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Preparation

Removing a major portion of the root system during the boxing process effectively induces drought stress. Although not a generally accepted practice, I’m convinced that drought stress in trees to be relocated can be significantly reduced by thoroughly irrigating them 2-3 times within a two to three-week period prior to any root pruning or excavation. This allows the tree to take up ample water for storage, which will help maintain normal life-processes, allowing roots to regenerate.

This important step should be especially helpful during periods of drought. The use of pesticides to prevent insect attack or disease development may also be beneficial in preparation and is discussed later in this article. Marking the trees orientation is also an important reference when replanting. It is preferable to replant a tree in its original orientation; primarily to reduce the risk of sunscald to the bark and to minimize the expenditure of stored energy to re-acclimate to the new orientation.

Pruning

The negative response in trees to pruning prior to relocation has been very clear to me. When I first began working in this field, it was common practice to prune heavily, often I would see more than 50 percent of canopy removed prior to boxing. At the time, I had just become a Certified Arborist and was anxious to improve on the process. I knew from basic tree biology that heavy foliage removal, which has a negative impact on tree health, would only add to the stress of severe root loss. Provided they receive adequate care, trees will respond naturally to root loss by shedding leaves (abscission) and/or branches as needed.

Foliage is necessary for energy production (photosynthesis) and the manufacture of hormones; both of which are critical for root regeneration. It didn’t take long to convince company managers to reduce pruning to a minimum, only dead, dying, diseased or structurally weak branches. Prior to this procedural change, relocated trees typically took several years or more to recover.

With the new pruning practices in place, I noticed a remarkable change in how the trees responded to boxing and relocation. It appeared that defoliation was significantly reduced and that roots regenerated more quickly. Other advancements have been made in tree relocation over the past few years, but none I’ve seen have been as significant as minimizing pruning.

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