The hanging hydrangea tree is also known as Hydrangea paniculata. This unusual specimen tree when mature can reach a height of 7 to 12 feet and a spread of 4 to 10 feet. The hydrangea flowers in late summer, with numerous white blossoms, which then turn to bluish-pink. It is fragrant, and its blooms attract butterflies. This is a fast growing tree, which is used as a specimen planting in landscape design. Reasons for pruning are to remove suckers from the base of the plant, to shorten the branches, and to thin out any competing branches. Pruning should be done in early spring as this tree produces blossoms on new wood.
Remove any suckers that are coming up from the ground at the base of the plant, and any shoots that appear on the lower section of the trunk. You want to maintain a bare lower trunk, as suckers take away valuable nutrients from the plant.
Shorten the branches that form the umbrella or crown of the tree by cutting them down to 2 to 3 sets of nodes per branch. A node is a small bump that will eventually grow into a side shoot on the branch. These side shoots are where the flower buds are produced.
View the structure of the hydrangea tree to determine if you need to thin out any competing branches. You will want to structure the tree so that it has approximately six main branches coming out of the trunk to form the umbrella/crown of the tree.
Cut out competing branches at the trunk. Use your judgment to determine which branches to cut out. As a guide the arching branches should begin at about 4 feet up on the bare trunk and be as evenly spaced as possible.