Found in U.S Department of Agriculture plant hardiness zones 4 through 8, the flowering weigela shrub (Weigela florida) is fast-growing and may require transplanting to a new location. Replanting weigela at the proper time of the year helps reduce plant stress, no matter which variety you choose for your landscape.
Plan ahead when transplanting a weigela shrub by pruning the roots at least two months before the fall transplanting date, generally in July or August. The process involves shortening the long roots to force new root growth closer to the trunk. The new root growth helps the weigela establish in the transplanted area by binding to the soil quickly. Root pruning is completed by cutting through the soil with a sharp spade in a circle around the plant about 15 inches from the trunk. Cut into the soil about 10 inches deep without removing any of the soil.
Pruning the weigela crown creates balance between the above-ground growth and root system. This transplanting step prepares the shrub for new growth after being moved to a new location. The best time to prune a weigela is after the spring blooms have faded in summer. You can wait to prune until late summer to early fall as the shrub begins to go into a dormant stage. Prune back overgrown branches, and remove branches that are growing inward or rubbing on another branch. Cut back the shrub while keeping the natural growth habit of arching, rounded branches.
Dig and move a weigela shrub in late fall through winter. The shrub is in the dormant stage during this time, so less stress is placed on the plant. Remove as much of the root system as possible when transplanting. Digging at least 15 inches from the trunk in a circular path around the shrub and a depth of 15 to 20 inches removes the portion of the roots that were pruned during the summer. Transplanting should occur before the spring flush of growth to prevent stress that can affect flower production.
Chose a transplanting location with similar features as the current growing area. Weigela prefers a well-draining soil and full sunlight. Root and crown pruning is not required to transplant a weigela, but it will prepare the plant and give it time to adjust to the smaller root size. Mature and established shrubs have large root systems and above-ground growth. Planning to transplant the season before or early in the current year gives you enough time to perform the pruning needed before removing the shrub.