Digging trees and shrubs for transplanting
Encyclopedia
When transplanting
Transplanting
For botanical organ transplant, see GraftingIn agriculture and gardening, transplanting or replanting is the technique of moving a plant from one location to another. Most often this takes the form of starting a plant from seed in optimal conditions, such as in a greenhouse or protected nursery...

 tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

s or shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

s from one location to another, digging the plant in preparation for moving it is typically the most challenging part of the job.

Anyone who grows trees and shrubs is likely at times to wish to move them. Transplanting involves digging the tree or shrub, moving it to its new location, and then replanting it. The most difficult of these steps, and the one which requires the most know-how, is digging. This article discusses digging up trees and shrubs to about 10 cm (4”) in trunk diameter.

For small plants – up to a trunk diameter of 2.5 cm (1”) or so – digging can be done with an ordinary garden spade
Spade
A spade is a tool designed primarily for the purpose of digging or removing earth. Early spades were made of riven wood. After the art of metalworking was discovered, spades were made with sharper tips of metal. Before the advent of metal spades manual labor was less efficient at moving earth,...

. It is important to do it right, but the work is not difficult and the odds of success are very good. For trees or shrubs with a trunk diameter over 2.5 cm (1”) in diameter, and up to as much as about 10 cm (4”) in diameter, there are good options available which make it possible for even the home gardener to transplant successfully. Note, however, that size and weight of the required root ball, and the work involved in transplanting, increases rapidly as the trunk diameter increases. Moving trees with trunks over about 10 cm (4”) in diameter is likely to require heavy equipment and specialized expertise. The cost of transplanting increases rapidly as the size of the tree increases, although there is almost no limit to the size of trees which can be transplanted successfully if one is willing to pay the price.

Steps in digging

Digging a tree or shrub in preparation for transplanting involves several steps. Various digging techniques can be employed, but no matter what approach is used, these steps must be attended to. The information covered here includes just the bare essentials. There are many factors which should be taken into account if one is to realize the best possible results. These considerations include the species of plant being moved and its condition, the soil conditions, climate, season of the year, and accessibility of the site.
  1. Selecting the tree or shrub to transplant, and determining the size of the root ball to be dug. An approximate rule of thumb is to use a root ball 20 times the diameter of the trunk (as measured just above the basal flare) for trunks up to 1.3 cm (½”) in diameter, 18 times the diameter of the trunk for 1.3-2.5cm (½-1”) diameter trunks, 16 times the trunk diameter for trunks 2.5-3.8 cm (1-1½”) in diameter, 14 times the trunk diameter for trunks 3.8-6.4cm (1½-2½”) in diameter, and 12 times the trunk diameter for trunks 6.4 to 10 cm (2½” to 4”) in diameter. For most trees and shrubs, the root ball depth should be about 20 cm (8”) for a 30 cm (12”) diameter root ball, ranging up to about 45 cm (18”) for a 120 cm (48”) diameter root ball.
  2. Cutting the root ball free from the surrounding soil so that it can be moved. This can be done in various ways. For small root balls (up to about 30–35 cm (12-14”) in diameter), an ordinary spade may be used to carefully slice the root ball free from the surrounding soil. The best spade for this purpose should be sturdily constructed, with a long, narrow blade cut square across at the tip. Such spades are sold commercially as “nursery spades”. Also available are the less sturdy “drain spades” - these have long, narrow blades which are usually rounded at the tip. Whatever type of spade is used, it is helpful to keep the cutting edge quite sharp. Keeping the blade clean and smooth helps also. Coating the blade with silicone lubricant or a similar product can help.Use the spade to dig a circle around the tree at a slight 15 deg. slanting inward angle. After you complete the circle, cut away some of the soil outside the circle and angle the spade into the bottom center of the rootball to cut any tap root at the bottom of the ball. If it's small ball tie a string (twine or a small strap) around the top outside edge of the ball to keep the soil of the ball compact and tight. Use the spade to lever the tree out of the hole. If it's a larger ball over 16" you will need a tractor boom, a forklift or a lifting tripod in order to lift the tree out of the hole using either straps pulled under the ball or forks underneath the ball. A 32" ball will weigh 300-500 lbs. depending on density of soil and moisture content. Years ago before the 1950s all trees were dug by hand. Years ago in order to move larger trees, the nursery men barerooted the tree while it was dormant to lessen the weight they had to move. Starting in the 1950s with Vermeer in the US and Optimal in Europe, modern hydraulic truck and loader mounted spades began to be used on a larger scale. Currently modern nurseries use machine tree spades to dig more than 90% of the trees grown today as they dig a uniform ball in lesss than a minute and automatically lift it out of the ground and place it into a burlap "sock" or "pocket" that holds the dirt inside of a metal wire basket that is tied and twisted into a tight package ready for shipping.

This stabilizes the root ball to help ensure that it stays intact during the transplanting process and is usually done B&B style (ball and burlap) or in a "WB" wire basket.
  1. Lifting the root ball out of the ground so that it may be transported to its new location may take either a strong back, a ball buggy or dolly or a machine like a loader or a forklift.


Depending on the digging method used, steps 3 and 4 may be reversed.

A fast handdigger can dig 20-20 16" root balls an hour or better. A machine spade can do 30-45 an hour. The bigger the ball the more time it takes to handle the tree properly.

There are several related new tree moving/growing techniques worth mentioning:

Dr. Bonnie Appleton Phd has been experimenting at Virginia Tech's Hampton Roads Virginia Research Station with a method that water washes the soil from the roots thus barerooting trees at any time of the year in order to examine and prune the roots for defects, (a major problem caused by the improper planting of young trees) then she washes the soil back around the roots with water to create a mud backfill whick locks the tree into the ground and eliminates air pockets in the soil. This also supplies the tree with a large influx of moisture to quickly grow new feeder roots.

Ren Heard of Lake Tree Farm in Virginia and Kentucky, uses a similar washing technique using a 750 psi orchard sprayer, combined with growing the recently dug tree in custom made baskets made of wood snow or sand fencing with more closely spaced pickets (organic pots) that air root prune the tree, eliminating circling roots (a major problem of pot growing), tap roots and wind roots are minimized, with a large increase of feeder roots thus allowing the tree to be replanted at anytime of the year with no transplant shock. This method is called Organic potting.

Digging table

Approximate root ball diameter to be dug
trunk diameter multiplier
up to 1.3 cm 20
1.3 to 2.5 cm 18
2.5 to 3.8 cm 16
3.8 to 6.4 cm 14
6.4 to 10 cm 12

Approximate root ball depth
root ball diameter root ball depth
30 cm 20 cm
120 cm 45 cm

Considerations

When transplanting any plant, preserving a significant fraction of the root system is necessary to maximize the chances of successfully re-establishing the plant in its new location. The practice of root pruning in preparation for transplanting can help concentrate the root system into a more confined area, thereby increasing the fraction of the root system that can be preserved.

In the case of trees and shrubs, the weight of a large root ball, and secondarily the weight of the tree itself, contribute significantly to the effort required to dig and move the plant.

Digging equipment

Trees and shrubs of all sizes may be dug up using simple shovel
Shovel
A shovel is a tool for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore. Shovels are extremely common tools that are used extensively in agriculture, construction, and gardening....

s.

Conventional earth moving equipment
Engineering vehicle
Heavy equipment refers to heavy-duty vehicles, specially designed for executing construction tasks, most frequently ones involving earthwork operations. They are also known as, construction equipment, construction plant, earth movers, engineering vehicles, or simply equipment...

 such as backhoe
Backhoe
A backhoe, also called a rear actor or back actor, is a piece of excavating equipment or digger consisting of a digging bucket on the end of a two-part articulated arm. They are typically mounted on the back of a tractor or front loader...

s and front loaders
Loader (equipment)
A loader is a heavy equipment machine often used in construction, primarily used to load material into or onto another type of machinery .-Heavy equipment front loaders:A loader A loader is a heavy equipment machine often used in construction, primarily used to load material (such as asphalt,...

 are also used.

Some nurseries use tree spades, which are specialized powered equipment dedicated to digging up trees and shrubs.

A specialized tool for cutting roots may also be used, possibly in conjunction with a lever
Lever
In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot point to either multiply the mechanical force that can be applied to another object or resistance force , or multiply the distance and speed at which the opposite end of the rigid object travels.This leverage...

age-based manual system for lifting the root ball.

In the case of extremely large trees, these have at times been moved by equipment designed for moving missiles.
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