How to Separate a Large White Hydrangea
- 1). Dig around the portion of the plant to be removed with a sharp spade.
- 2). Loosen the clump by gradually working the end of the spade beneath the roots until they can be easily lifted from the ground.
- 3). Wrap the roots in moistened burlap to keep them from drying out.
- 4). Prepare a new planting hole that is two times the width of the roots and just deep enough to replant the hydrangea at its original depth.
- 5). Prune off any damaged roots with a sharp knife.
- 6). Place the roots into the new hole and return the loosened soil. Pat down to firm and water until the soil feels evenly moist.
- 7). Spread 2 to 3 inches of organic mulch beneath the plant.
- 8). Keep the soil around the plant lightly moist at all times during the first season after separating. Water only when conditions are dry during subsequent growing seasons.
Source...