Although these may have been replaced by newer methods, there are two ways to transplant mature shrubs that I'm aware of. Both require a bit of work and patience on your part.
1. Use a sharpshooter spade driven downward some distance, perhaps a foot or so, around the perimeter of the selected plant/bush to cut the existing horizontal and vertical root system. This causes the plant/bush to form new feeder roots within the cut area. After waiting some time, perhaps 2 to 4 months, the plant is then dug out using the same general and original area as your guide to removing the root ball and entire plant. Slip some medium such as burlap, plastic sheeting, or whatever under the root ball to keep the soil ball intact and transplant immediately into the new planting hole which has been previously prepared, removing the "carrier material" before refilling and packing the hole as necessary and then watering in well to settle.
2. The second method is essentially the same as the first although there is no waiting period for the plant to regrow any lost root system. This method will require that you trim 1/3 to 1/2 of the top growth back to make up for the now smaller and less efficient root ball that is remaining.
Both methods will benefit from applications of root stimulator once monthly for several months or until planting shock wears off. Typically, it also benefits the plant if you do not add high nitrogen type fertilizers until the plant/bush is settled in and growing well as this will promote top growth which the plant may or may not be able to handle because of the reduced root system. As with any new planting, water well and often to reduce planting stress.
Hope this helps although quite honestly, there are some shrubs of size that are far easier to replace using "new" container grown specimens than trying to transplant older, albeit healthy existing specimens that you may already have.
Steve
This message was edited Mar 22, 2014 8:21 AM
