How to Root Prune and Transplant Field Grown Trees and Shrubs
Trees growing in the landscape or field growing in a nursery need special care when transplanting to ensure success. Here’s how to do it.
Selection and Timing
Select only healthy trees that are capable of successful transplantation. Root prune established trees carefully and well in advance of transplanting.
- Root prune a minimum of 3-4 months prior to the date needed.
2. Be sure the tree is well hydrated before cutting any roots.
3. Rule of thumb is for every inch of caliper a tree will need 10 inches of root ball. ¹ Example – A tree with a diameter breast height (DBH) measured at 54 inches above grade, of 10 inches would need a root ball a minimum of 100 inches in diameter: 10 inches DBH X 10 inches = 100 inches. Note: for trees over 24″ DBH, root ball size can be reduced to 7″ of root ball for every inch of Caliper.1
Root Pruning Prior to Relocation
Do not cut all the roots of the tree at once as it could shock and/or become unstable.
- If the tree is not too large, a tree spade can be used to prune roots prior to relocation.
2, For larger trees or where a tree spade is not feasible, cut roots to a depth of 18-24 inches on at least two sides of the tree using a sharp edged balling spade, reciprocating saw or other appropriate sharp cutting tool.
3. This will create an opening (trench) that can be back filled with soil to prevent severed roots from drying out and facilitate root regeneration.
4. Some movers opt to cover the freshly cut sides of the root ball with plastic sheeting to prevent desiccation of the new roots.
5. The trench is then backfilled with soil leaving the plastic sheeting in place for easy extraction when the tree is ready for relocation.
6. If a tree spade was used, a trench will not be created, and backfilling is not necessary.
Staking and Watering
- Once root pruning and backfilling have been completed, staking and bracing is recommended to provide support.
- Following root pruning, it is essential that the root ball be kept moist to maintain tree health and encourage new root initiation.
Final Preparations for Relocation
3-4 months after the initial root pruning, the tree should be ready to move.
- When it is time to relocate the tree, cut roots all the way around the tree (360 degrees). If plastic sheeting was used, cut roots at the same distance from the trunk as before.
- If plastic sheeting was not used, cut roots about six to twelve inches wider than where originally cut. This will help capture the new roots that formed in the backfilled trench following the earlier root pruning. The goal is to sever all the lateral roots extending out from the tree as well as those on the bottom of the root plate.
Determining Depth of Root Ball
- For root balls with diameters less than 20 inches, the depth should be at least 65% of the diameter of the root ball.
- For root balls with diameters greater than 20 inches the depth should be at least 60 percent of the diameter of the root ball. 3
Example – If a tree has a root ball diameter of 30 inches, you should dig down at least 18 inches: 30” X 60% = 18”.
- Dig until the entire root system has been severed, freeing the root ball.
- Some movers insert heavy gauge metal piping under the tree’s root ball to facilitate extraction and transportation with a crane or other equipment. 2
Managing the Extracted Root Ball
Wrap the resulting root ball in burlap or plastic sheeting, or place it into a container before you move it to the new planting location. If using a tree spade, the cradle of the spade will suffice.
- Take all necessary precautions to maintain the integrity of the root ball so it does not fall apart during transit or installation.
- Pay close attention to the moisture content of the root ball and ensure that it never dries out. Young roots are susceptible to desiccation and can easily die if they dry out.
- Properly prepped and maintained, trees can remain alive for many weeks prior to planting if monitored closely for water requirements.
Planting in the New Location
- Use a balling or tree spade to dig a hole at least 1.5 – 2 times the diameter and about 90% of the depth of the root ball.
Example – If a tree has a diameter of 30 inches, the width of the hole should be at least 45 – 60 inches wide. The root ball should sit 1 – 2 inches above grade to allow for settling and mulching.
- Remove any non-biodegradable materials covering the root ball (e.g. containers or plastic sheeting).Natural burlap should be left on the root ball as it can easily break down in the soil.
- Carefully lower the tree into the planting hole setting it on undisturbed soil. Try not to disrupt the root ball or damage the trunk. Make sure that the trunk flare is at or near grade.
- Back fill with soil, water thoroughly to eliminate air pockets and stake.
- A raised berm made of mulch – not soil, can help create a temporary tree well to hold water. Place around the outer edge of root ball and not on top of it or up against the trunk, be sure that you can see the root flare (1st order root).
Water Requirements After Transplanting
- Newly planted trees will need supplemental watering until they are fully established: 3-4 months per inch of trunk caliper.
Example – If a tree has a trunk caliper of 5 inches, it will take about 15 -20 months or about a year and a half to establish.
- UF/IFAS Extension recommends applying 2 gallons of water per day per inch of trunk caliper for the first two weeks.
Example – If a tree has a trunk caliper of 5 inches, you will apply 10 gallons per day (5” X 2 gallons) for the first two weeks.
- After two weeks and until the tree is fully established, provide water at the same rate at least 3 times per week.
- A dedicated bubbler connected to a well-maintained irrigation system is highly recommended and used until tree has established. At this point assess whether you still need it and if so, move out to the drip line.
By following these guidelines, you can achieve success in transplanting these valuable community assets.
By: Michael Orfanedes, Ph.D., Extension Agent IV, UF/IFAS Extension and Donna Castro, Education Specialist, UF/IFAS Extension Broward, with Way Hoyt, ISA Registered Consulting Arborist
¹Table 6 – Root ball diameters – field grown trees; American Standard for Nursery Stock (ANSI Z60. 1-2004
2Tom Gurley, certified arborist with Tree Movers Inc., Boynton Beach, FL; personal communication.
3 1.6.3 Root ball depth – Root ball diameters – field grown trees; American Standard for Nursery Stock (ANSI Z60. 1-2004).