HOW TO TRANSPLANT
You’ve invested time and money in your landscape, but landscapes evolve and mature over the years. At some point you may need to make changes. These changes could include moving established trees or shrubs.
Reasons to Relocate a Tree or Shrub
Transplanting mature trees and shrubs is possible, although the process is not as simple as planting new ones. There are several reasons to relocate an established landscape plant. Among them are:
- Home additions or hardscaping projects that require plants to be moved.
- Relocation to a new address where you’d like to move a favorite tree or shrub.
- Foundation plants outgrow their current space and need a new home.
Assessing the Transplanting Project
First, decide if you can handle the job. It isn’t easy. The project requires root pruning the season prior to transplanting, digging up the plant to be moved, digging a new planting hole, moving a heavy plant with the root ball attached, positioning the plant and refilling both holes. Providing plant care after the transplant is critical as well. Do not consider transplanting if you will not be able to provide water for the plant for at least the first year after transplanting.
Make sure the tree or shrub is a manageable size. Shrubs up to three feet tall and trees one inch or less in diameter (measured six inches above the soil level) can be moved without digging a solid root ball. These and most plants three to four years old may be moved as bare root transplants. Larger or older plants will need to be dug and transplanted with the root ball intact.
For a transplant to be successful, you must include as much of the plant’s root system as is reasonably possible. In general, you’ll need at least 10 to 12 inches in diameter of root ball for every 1 inch of trunk diameter.
Example: If a tree is three feet in diameter, you will need a root ball that is 30 to 36 inches in diameter.
The depth of the root ball also increases proportionally. Include as many of the lateral roots as possible. Since these roots are near the soil line, a root ball that’s generally 12-24 inches deep will include those roots.
A root ball with soil and plant attached will weigh about 100 pounds per cubic foot, so have the necessary machinery or manpower available to move it. The bigger the tree, the less likely a do-it-yourselfer you will have a successful transplant.
Fall, late winter or early spring are the best times to transplant. The move should be done after leaves fall in the autumn or before new buds break in the spring. If you are in doubt as to the best time to transplant in your area, your local Cooperative Extension office is a valuable resource.
Very large landscape plantings can be moved with a truck-mounted hydraulic tree spade. Depending on the size of the machine, trees up to 50′ tall can be successfully transplanted. You will need to find a professional to do this for you.
Evaluating the Location and the Plant
Transplanting is stressful for trees and shrubs. Make sure your plants are up to the task.
If the plant is doing well in its current spot, find a new location with similar environmental characteristics.
A plant that is not healthy may not survive transplanting. If you still want to move the plant, determine the problem, treat it and postpone the move until the plant is healthy. If the plant is not doing well, there are several possible reasons:
Pests or disease — if the tree or shrub is damaged or seriously affected by either of these it may be best to replace it rather than transplant.
Sunlight requirements — if the problem is the environment (too much or too little sun), determine how much average daily sun exposure the new location receives.
Soil type — poor growth may be a result of the soil and moving the plant may not remedy the situation. Do a soil test to determine whether the plant is suitable to your existing soil conditions. Adjust the soil pH to better fit the plant or find a new plant that will thrive in your soil.
Here are some other plant relocation considerations:
- Trees with long vertical tap roots like walnut, oaks and pines are difficult to transplant.
- Many trees that grow in sandy soils may have longer tap roots and wider lateral root systems than many landscape plants growing in more clay-based soil. This means more digging prior to transplanting.
- Moving native plants from wooded areas to the lawn may sound good, but the success rate is low. Find nursery-grown natives to install in the landscape.
- Deciduous plants usually transplant better than conifers. Shrubs normally relocate better than trees.
- If plants are being moved because of a space issue, don’t repeat the same mistake. Allow for plenty of room in the new location.
- The spot you transplant from will still have approximately 75% of the moved plant’s root system left in the ground. Expect some extra work to prepare this area for new plantings or turfgrass.
- Check right-of-way, overhead/underground utilities and property lines before digging. Call 811 before beginning any excavation to schedule an underground utilities location check.
Please call 811 before beginning any excavation, check for underground utilities.
Root Pruning Before Transplanting
Water and nutrients are absorbed by tree roots, but the large roots nearest the tree trunk absorb very little. Tiny feeder roots that extend well beyond the tree perform most of that function. Root pruning stimulates small new feeder roots nearer the trunk. These new roots will be dug up as part of the root ball for transplanting. Root pruning is a familiar practice for bonsai growers. It is also essential when transplanting mature plants.
A tree or shrub to be transplanted in fall should be root pruned in the spring before new buds appear. Plants to be transplanted in spring should be root pruned the previous fall after the leaves drop. Follow these steps:
- Water the soil the day before pruning. This softens the ground for digging and helps reduce stress to plant roots. It also helps keep the soil attached to the roots.
- Wrap or tie the lower branches up to protect them and keep them out of your way while digging.
- Mark the area of the zone to be pruned. (Remember, a 10-12 inch diameter of root ball for every one inch of trunk diameter.)
- Begin cutting a trench, using a flat spade with the face turned away from the plant. A sharp edge makes a cleaner cut that will make digging easier. If you encounter large roots, cut them with loppers.
- Continue digging the trench, cutting roots as you go, down about 24 inches, to reach as many lateral roots as possible. While digging, separate topsoil from subsoil to return to the trench after pruning.
- After trenching around the entire plant, the root pruning is complete. Do not dig underneath the plant. Replace the subsoil and then the topsoil.
- Water thoroughly and untie the branches.
New feeder roots grow from the cut ends. You must include these new roots with the transplant (the whole idea of root pruning). At transplanting time, plan to cut the root ball four to six inches out from where the roots were pruned.
Performing the Transplant
When transplanting time arrives, the basic steps are the same as root pruning — with a few key differences.
- Water the soil the day before to soften the ground, reduce stress to plant roots and help keep the root ball intact.
- Dig the new planting hole and have it ready before the transplant. Dig the hole two-three times as wide as the root ball, but no deeper. Moisten the hole before installing the root ball to help reduce transplant shock.
- Mark one of the branches with a string or other marker to denote its orientation to North, South, East or West. You’ll want to replant it with the same orientation. Tie the lower branches up to protect them and keep them out of your way while digging.
- Gently remove the topsoil from the top of the roots near the trunk and mark the area to be dug. In order to include newly-grown roots, mark four-six inches further out from the trench where the roots were pruned. Begin digging outside of this mark.
- Standing inside the marked circle, begin digging with a flat spade, keeping the face turned away from the plant. Continue digging around the plant. Dig progressively deeper, shaping the root ball as you go. If you encounter large roots, cut them with loppers.
- When you have cut around the plant down to the proper level to include the roots, begin digging underneath the root ball.
- Before cutting the root ball completely, place a tarp or sheet of burlap into the hole beside the ball. Dig under the ball and cut any last remaining roots below. Tilt the root ball over onto the tarp for wrapping and moving.
Always lift the plant from underneath–never by the trunk.
Roots must be kept moist or they will die. Any plant that cannot be installed in its new location immediately after digging should be kept in the shade and the roots kept moist.
If you are transporting large plants to a new location on the highway, do not carry them in an open vehicle. Use an enclosed truck or van or cover the plant. Keep the roots moist by wrapping them in wet newspaper or burlap.
- Place the plant in the new hole. Orient it as it originally grew, with the marked branch facing the proper direction.
- Fill the hole halfway with soil. Water the soil and allow it to soak in before filling the hole completely. Tamp the soil gently around the roots and water thoroughly.
- Stake the plant, if necessary, and add mulch to cover the bare soil, taking care not to pile mulch against the trunk or stems.
Be diligent about watering the plant during the first year after transplant, while it establishes itself in its new place.