4.5 minute read.
One of the first questions our customers ask in regards to tree moving is “What is the likelihood a tree will survive being moved?”
A better question might be “Can this tree species survive the new environment once transplanted?” Fortunately, millennia of horticulture trial and error methods have yielded modern industry standards which, if followed, increase the likelihood of a tree surviving a transplant. Many trees will adapt to new soils within reason. There are some obvious exceptions of course. Only one species of Palm is common in our region of the Pacific Northwest and you’re unlikely to find a Doug Fir in the middle of a desert.
In our experience most tree moving is localized to the “climate zone” where that particular species thrives. Were we to relocate a native tree from one point to another within the PacNW Willamette Valley climate zone, chances are pretty high that the tree will take root easily enough in a new location. Given enough sunlight, proper nutrition in the soil, and a consistent watering schedule during the first growing season at least, it should adapt just fine. But a tree is a living organism and even if best practices are followed, there are no guarantees that a tree will survive being removed from one location and transplanted elsewhere. So we just have to follow best practices.
(Nursery standards indicate that a 9” (+/-) rootball mass carries a sufficient amount of roots to sustain a 1” diameter (aka “tree caliper”) tree. So a tree with a caliper (measured 6” above ground) of 9” can easily be moved using an 80” tree spade. But even these standards vary depending on species and time of year. If you would like to know the price tag for moving a tree check out this article on pricing.)
Having a certified arborist as a consultant on the project helps increase the tree’s survival rate. A little horticulture knowledge would be preferable as well. Some experiential intuition doesn’t hurt. And if they have, say, 100+ years accumulated on-the-job experience passed down through three generations then you would have yourself a power house of knowledge on the process of tree relocating (Hey that’s us!). There really is no getting around hiring a professional arborist for this type of work.
“But you’re cutting the roots. Doesn’t that kill the tree?”
Not when they are cut in a controlled, industry approved fashion. Like following the 9” of rootball mass to 1” caliper trunk standards. “Root pruning” is also a common practice and It is used primarily to force new feeder roots to grow within the rootball prior to a move. Doing so gives the tree more resources with which to gather food and water so when the time for a move comes it is better prepared to adapt to a new location. We will do this when the occasion calls for it.
For example, sometimes a 20’ diameter rootball for a large tree is undesirable. Logistics may prohibit us or the machinery involved might not be sufficient to acquire that size. In that case we would begin root pruning a year and in some cases up to two years in advance. Especially the harder woods like Oak as the branches and roots grow at a slower rate.
Maybe the trunk diameter of the Cherry tree is 8” and general nursery standards say our 80” spade will suffice but experience tells us this project would require root pruning to force as many feeder roots as can be packed into the rootball because Cherry trees are notoriously difficult to transplant.
“But doesn’t the tree need all of the “critical root zone” to survive?
Allow me to uproot a common misconception. Most tree roots grow within 3’ below the surface and at least as wide in diameter as the drip-line of the canopy. So picture a full grown tree with roots filling a 24” deep pot as wide as the canopy. The bigger stabilizer roots keep the tree upright while the smaller, tendril-like roots (feeder roots) do most of the food and water gathering.
The “root system” that forms the mirrored image depicted in some diagrams is more often (though not always) the symbiotic relationship between the network of roots and micro-organisms (mycorrhizae) in the soil. This network can extend beyond the critical root zone and into the territory of other trees and shrubs thereby forming one continuous network of roots, bacteria, micro-organisms, and fungus which break down the organic debris in the soil and feed it to the tree.
(As an adjunct to a consistent watering schedule and guying when necessary we can provide tree vitamins upon request to assist the growth of the micro-organisms thereby assisting the tree in its adaptation to the new environment.)
While digging up one tree may slightly disrupt the immediate eco system, the individual tree doesn’t need the entire critical root zone to survive a transplant.
“Ok so what can kill a tree during the relocating process?”
The important factors to consider when relocating a tree to a new environment are ratio of rootball mass to trunk diameter, soil conditions, sunlight, and a consistent watering schedule for at least one growing season after transplanting (this varies based on species and time of year).
But even too much of a good thing can hurt. Suppose the tree is planted at the bottom of a hill where rain runoff accrues into a pool that submerges the trunk in 6” of water. Unless the tree species has adapted to survive in wet environments (think everglades) the pool of water will suck all the oxygen out of the soil and suffocate the roots. Which is why good soil drainage is a necessity.
Maybe everything went fine during the transplant but you piled several inches of bark dust above the root crown which compromised the bark and killed the tree. Some contractors we knew were baffled on a project when they brought in a load of topsoil to the construction site, planted a bunch of trees and found that they all died. Well, most topsoil in our area is river silt and lacking the nutritional value needed for any kind of vegetation to survive and had they added compost, organic debris, and/or fertilizer to the soil they would not have had the same problem.
Given that there are so many variables to the survival and health of a tree during and after a transplant (a proper aftercare routine can make or break the tree also), there really is no getting around hiring a professional arborist for a tree relocating project. Though no guarantees can be made that a tree will survive a transplant, our decades of experience following best practices and thousands of moved trees under our belt have enabled us to maintain an approximate 95% success rate.
