By pruning right after the blooms have faded, you allow the plant time to set buds for the next year. Oakleaf (H. quercifolia) and bigleaf hydrangea (H. macrophylla), including Nikko Blue and all the other pink- and blue-flowering cultivars, bloom from buds set the previous year.
Nov 25, Cut your hydrangea when it is getting too big for your space. You may have planted your hydrangea with a designated area in mind for it to grow. Limelight hydrangeas can grow up to 6 feet ( m) tall, so you might have to cut them back if they outgrow their bushcutting.buzz: 17K.