In the spring, the rhododendron shrub displays large blooms in white, yellow or shades of pink or lavender. Growing from 3 to 8 feet tall and wide, rhododendrons are frequently seen in a wooded landscape, at the rear of a flower bed or surrounded by fellow acid-loving azalea. You can transplant rhododendrons in fall or spring.
Select a planting location in dappled shade or part sun. The optimal soil pH level for rhododendrons is between 4.5 and 6.0. The soil pH level can be tested using a kit available from your local garden center. To lower soil pH level, aluminum sulfate can be applied to the soil according to manufacturer's instructions.
Water the transplant rhododendrons thoroughly the day before the planned move. Measure the widest part of the transplant rhododendron by placing the extended measuring tape through the center of the shrub. That measurement will equal the diameter of the drip line, an imaginary circle on the ground around the trunk of the shrub.
Dig the new hole before removing the transplant. Use the diameter measurement taken in the previous step to dig a hole that width and about 12 inches deep, though loosening the soil down to 18 inches will ensure proper drainage. The depth of the hole may need to be adjusted once you bring the transplant rhododendron to the hole.
Dig around the rhododendron at the drip line and down 12 inches. Try to get as much of the root system as possible. After you have dug all the way around the rhododendron and as far under as you can, push the rhododendron to one side and work the tarp underneath it. Using the shovel for leverage, work the shrub onto the tarp from the opposite side. Tie the tarp to contain the rootball.
Relocate the dug-up rhododendron to the freshly-dug hole using a wheelbarrow. Work the rootball into the hole so the top of the ball will be at or slightly above ground level. Remove the tarp by pushing the shrub to one side, folding the tarp up snugly to the bottom of the rootball and then pushing the rootball in the opposite direction to completely remove the tarp.
Backfill the hole. Organic matter, like compost or leaf mold, can be added when backfilling the hole. Prune back 1/3 of the outermost branches and any dead or broken branches. Apply 2 inches of mulch starting about 3 inches from the trunk of the shrub.
Water the transplanted rhododendron thoroughly. Water about every 10 days until the first frost if there is no saturating rainfall. Continue to water regularly during the second year of growth.