Plant a new hydrangea bush either in the early summer or fall. If moving an established hydrangea, plant it in the winter when it is dormant.
Plant a hydrangea that is still blooming, so the right variety and color can be selected. Avoid planting a hydrangea in the early spring because a late frost may harm it. The hot, dry conditions of midsummer also lessen the plant's chances of survival. Water the plant well each day until it becomes established but make sure the soil is well-drained. Hydrangeas do best when planted in a spot with morning sun and afternoon shade.