Nothing can grace a yard like well-established trees,but if you’re starting with saplings, it can take a generation or more for your trees to reach full bloom. Of course, you’ll enjoy the benefits of maturing trees along the way, but it can still be a long wait for real summer shade and the balanced visual heft your landscaping needs.
This helps explain the increasing popularity of truck-mounted tree spades. A large tree spade can uproot a fairly mature tree and plunk it down in your yard in a matter of hours, and in the process shave a decade or more from the wait. It’s an appealing option.
If you’ve been thinking of having a large tree transplanted, there’s really quite a lot to consider. Not every property is right for mature transplants. Cost is also an issue. Still, transplanting mature trees makes good sense in many cases, so let’s consider the process, from the ground up.
A tree spade is a machine that uses hydraulics to force triangular blades into the ground so a conical plug of earth can be removed. Most larger tree spades are mounted on modified trucks with outrigger stabilizers that support and level the four blades. The two rear blades are mounted on a hinged framework that allows the back of the machine to swing open when approaching a tree.
Tree spades come in a variety of sizes to accommodate a wide range of trees. Because the size of the tree influences the machine that’s used, make your requirements clear before you hire someone to do the work. Standard equipment ranges from 20-in.-dia. nursery machines to 92-in. behemoths. The diameter refers to the width of the soil plug as measured at the surface. This measurement divided by 10 defines the size of tree that can be moved successfully. A 20-in. spade, for example, is pretty much limited to a tree with a 2-in.-dia. trunk as measured 12 in. from the ground.
At the other extreme, a 92-in. spade, can transplant a 30-ft.-tall tree. The very size of these rigs is limiting, however. Job-site maneuverability can be a problem, and with a 92-in. bite the soil plug alone can weigh 12,000 to 14,000 pounds. Greater equipment costs, plus higher prices for really big trees, substantially limit the customer base.
Each planting requires the operator to first remove a soil plug from your yard, thereby creating a hole for the new tree. Typically, this plug is then hauled to the nursery and dropped into the hole left by a previous removal.
At the nursery, the operator opens the gate-like rear half of the spade assembly and centers the blades around the tree. With the gates closed, the operator engages the hydraulics that drive the pointed blades into the ground. The trunk is strapped to the machine to keep it from shifting as it’s transported.
Then, the operator uses a second set of hydraulics to lift the root plug from the ground, arching it over the back of the vehicle. In this way, the captured tree lies horizontally across the top of the truck for transport.
At the planting site, the truck swings the tree back to a vertical position and centers the plug over the hole. After the plug has been lowered into place the blades are withdrawn.
When planning the job, keep in mind that a truck-mounted tree spade requires room to maneuver. Steep grades, overhead wires, the proximity of buildings and other location features can affect the feasibility of the transplant.
The 10:1 ratio of spade diameter to tree diameter is less a mechanical limitation than a root-mass requirement. A tree that is uprooted must retain enough undisturbed root mass to replace moisture lost through the leaf structure by transpiration.
To improve survivability in spring and summer, you might use a larger machine to transplant smaller trees. There are also commercial products that can be sprayed on leaves to temporarily reduce transpiration. And finally, tree species vary in transplant hardiness. A spruce, for example, transplants well, so you might get away with planting a 6-in.-dia. spruce with a 50-in. spade.
Local conditions vary substantially, so it’s not possible to say exactly how much you’ll pay to have a mature tree planted in your yard. The two variables are the cost of the tree and the cost of moving it to your site. Unless you’re transplanting a tree from your own property or have been offered one for free, you’ll probably buy from a local nursery.
The care you give your new tree after it’s planted will greatly affect its chances of surviving that first, crucial year.
Adequate water is another critical factor. Because it’s just as easy to kill a tree with too much water as with too little, you’ll need to watch the situation carefully. Soil type is the biggest factor. Heavy clay soils don’t absorb water very well, so overwatering is more likely in clay. A good test of soil percolation is to flood the hole one-third full of water just after it’s dug. If most of the water soaks away in about an hour, overwatering will be less likely.
In any case, after the tree is planted and backfilled, flood the seam thoroughly (Photo 6). With non-clay soils, repeat the process a few days later, then water normally, just as you would your lawn.
As for fertilizer, wait until the following growing season. The goal in the beginning is not tree growth but root healing. If you add anything, make it a root stimulator, which is primarily vitamin B-1. These common plant starters may contain some fertilizer, but will have little or no nitrogen. The best time to add a root stimulator is when you flood the seam initially.