All species of hydrangea grow best when planted in areas of morning sun or all day dappled shade. Moving a hydrangea that isn't growing or blooming well can help promote a healthier, more luscious plant.
The best time to transplant hydrangea bushes is in the late fall or winter when they're dormant, reducing transplant shock. Dig as much dirt as possible around the root ball and transplant it with the hydrangea. Give the plant one deep watering after the transplant. Keep it well watered in the spring and summer.
Early Summer or Fall
If you can't transplant in the winter, transplant the hydrangea in the early summer, after the threat of late spring freezes is past, or in the fall, after the height of summer heat is over. Water the plants well after transplanting to help reduce transplant shock.
Keep the plant well watered to prevent withering, but don't overwater, which encourages root rot. Deep watering with a hose is more beneficial than watering with a sprinkler. Transplanted hydrangeas may need supplemental watering for the first two summers after being transplanted to become really well-established.