Evergreens are considered sturdy plants with generally tough constitutions, but they are vulnerable during and after transplanting. Keeping evergreens well- but not over-hydrated is the main key to a successful transplant and preventing shock. According to North Dakota State University, a regular watering regimen should be followed after transplanting for the number of years equal to the diameter of the evergreen trunk at the time of transplant. For example, an evergreen with a 3-inch diameter trunk should be irrigated for three years after transplanting to ensure it is well established in the soil and will thrive over the long term.
Transplant your evergreens when they are dormant in the winter or early spring, before new growth emerges, to lessen the threat and effects of shock.
Prepare a planting location by excavating a hole that is twice the diameter of the root mass and half again as deep. Loosen the soil in the sides and bottom of the hole with a shovel or spade.
Enrich the planting area by digging in several pounds of well-aged livestock manure, peat moss, leaf mold and/or compost. Use enough organics to cover 3 to 5 feet of the wider planting area with at least 3 inches of these materials before tilling them into the top foot of soil. These materials will ensure the evergreen is not stressed for nutrition, a condition which can cause shock.
Add some of the soil amendments to the bottom of the planting hole to bring the depth of the hole equal with the depth of the root ball. Slide the evergreen from its nursery pot or burlap wrap and set in the prepared hole. Add or subtract compost from under the root ball if needed, to bring the top of the root ball level with the surrounding soil.
Backfill the amended soil around the root ball half way up the sides of the hole. Water in the evergreen until the root ball and surrounding soil is drenched. Backfill the remaining soil and tamp down with your foot to collapse any air pockets. Water again to drench the top 12 inches of soil. Add more amended soil to fill in any divots where the soil has settled with watering.
Mulch around the base of the tree and 3 to 5 feet of the wider planting area with 3 to 4 inches of organic material such as compost, leaf mold, shredded bark, cocoa bean hulls or similar materials.