Transplanting Trees and Shrubs

Cuyahoga Community College Plant Science and Landscape Technology students begin to shape the root ball of this Japanese maple

The annual late summer buzz of the cicadas is a precursor to the coming fall. The days are beginning to shorten and soon the trees will begin to show some early autumn color. The late summer and fall seasons are perfect for transplanting trees and shrubs. The summer warmed soils give plenty of opportunity for root growth and the shorter cooler days reduce the amount of water loss from the plant.

If timing permits, root pruning should be done in the spring prior to the fall transplanting. The location of the root pruning should occur inside the diameter of the ultimate root ball to be dug. It has been found that roots do not develop lateral roots as a result of root pruning like branches; rather all the new roots develop at the tip of the remaining root. By pruning the roots further in it allows for more of the new fibrous roots to be contained in the transplanted root ball.

Root pruning is often considered a luxury when transplanting plants. All too often the timing of the move is predicated by other factors that don’t allow for such preparation. Many successful transplants have occurred without any root pruning at all.

The first step in transplanting should involve locating the new planting site. The longer a plant stays out of the ground awaiting a new home, the less chance of survival. Prepare the new location prior to digging the plant; this will greatly minimize the amount of time the plant will be above ground, thus improving the survivability. The plant should be tagged to orient the plant in the same direction in its new home; this shortens the acclimatization period and prevents damage like sun scald or frost cracks.

The size of the root ball is dependent on the size of the tree. There are multiple resources available with varying figures. A good general rule is a root ball diameter 10 to 12 times the trunk diameter. The trunk diameter is measured at 6” from the soil for trees up to 4”. If the diameter is larger than 4” at 6” from the soil use the diameter at 12” from the soil. The depth of the root ball is less critical as long as you are roughly 2/3 the width or over 18”, as most of the tree’s root are in the upper 12” to 16” of soil.

Tie the branches up before you begin digging so they are out of your way. Dig a large trench around the plant at a diameter larger than the ultimate root ball size. Dig to the depth the root ball will be. With the trench dug begin shaping the root ball down to the size desired; this is easiest done with a nursery spade. Gradually bring the bottom of the root ball down to a smaller diameter than the top leaving just a small diameter of soil still attached to the bottom of the hole. Now dig under the root ball on one side only; creating a cavity under the root ball. Take a piece of burlap four times the height and the diameter and roll half of it up. Place the rolled up end into the hole under the root ball in the cavity created. Now knock the root ball off the still attached soil onto the burlap. Unroll the rolled end and your root ball should be sitting in the center of your piece of burlap. Next, tie up all the corners tight and you should be able to safely move your shrub or tree to its new location. Twine may be used to cinch the burlap tighter. Nurseries use special nails to pin the burlap tighter.

Root balls larger than 24” should be drum laced, a technique best left to a professional. Not necessarily due to the complexity of the technique but rather the weight of the root ball at such a diameter. The integrity of the root ball is extremely important; one mistake can ruin hours of invested time.



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Volume 4, Issue 17, Posted 12:18 PM, 07.31.2008