Timing

• To avoid cutting off the next season's blooms, a pruning session should depend on a hydrangea's blooming time. Some hydrangeas set their next year's blooms in August, while others bloom every year on new wood.
  
  

Summer Pruning

• For mophead, lacecap, or oak leaf hydrangeas, which bloom on old wood in pink, blue, or white, careful summer pruning can take place up to August. In August, September, and October, these bushes set their blooms for the next year, and pruning at that time may cut off the blooms. Pruning in spring should only include nonflowering branches.
  
  

Yearly Pruning

• Hydrangea paniculata and Annabelle hydrangeas set their flowers on new wood, and don't have specific pruning requirements. Gardeners prune these bushes back to their main cane in fall, to regrow and bloom in spring. A spring pruning on these bushes should be minimal, and include only nonflowering branches.