But when to prune them? Prune fall blooming hydrangeas, or old wood bloomers, after they bloom in the summer. If you prune old wooded hydrangeas in fall, you are cutting off next seasons blooms. Summer blooming hydrangeas, or those that bloom on new wood, are pruned in the fall, after they stop blooming.
Cut back any clearly dead branches, which are brittle and snap off easily. This can be done in the fall or any time you see a dead branch. To reduce the size of a hydrangea that blooms on new wood, cut off about one-third of each stem in late fall or early spring before it begins to leaf out.
Prune these hydrangeas only after bloom in the summer and not in the fall. Old wood hydrangeas start developing their bloom buds for next year in August and September. If you don't prune your hydrangeas real soon, then it is better to wait until next year. Otherwise you won't have any blooms next spring.
Some hydrangeas' branches often fall over under the weight of their blooms, especially after overhead irrigation or after a good rain. One way to alleviate this flopping is to cut the stems to a height of 18 to 24 inches to provide a sturdy framework to support new growth.
To prepare hydrangeas for winter in colder areas, add a thick layer of mulch around the base of the plants to protect the crown and roots from freezing temperatures.
Prune back stems to just above a fat bud — called a heading cut — in fall, late winter or spring. These plants have conical-shaped flower heads. I recommend leaving the dry, tan flower heads on the plant to provide some winter interest in your landscape, so I wait to prune these until late winter or spring.
Wrap with winter protection.
During the winter, make a DIY A-frame wire cage out of burlap and chicken wire to protect your hydrangea plant. This cage will protect it from winter winds, heavy snowfall, and cold temperatures.
However, stop deadheading hydrangea shrubs in mid to late fall, leaving any spent blooms in place. This not only provides winter interest, but also ensures you don't remove the buds that will become flowers next spring.
Hydrangeas that bloom on new wood can be safely pruned in late fall once the plants have gone dormant or in early spring. Next year's flower buds won't be formed until late spring the same year they bloom, so there is no risk of removing the buds if you prune in fall or spring.
While some plants bloom on new growth, others primarily set flower buds on old wood. Regardless, it is best to wait to prune all hydrangeas until spring. In the fall, hydrangeas (and all trees and shrubs) are in the process of going dormant. They do not produce very much new growth until the following spring.
Without going through the deadheading process, hydrangeas will not produce as many flowers and the few produced may not grow as big to their full potential.
Hydrangeas that bloom on new wood require pruning in late winter or early spring. Prune to shape, cutting back to about two feet. The pruning promotes new, sturdy growth, which provides the blooms next season.
Prune fall blooming hydrangeas, or old wood bloomers, after they bloom in the summer. If you prune old wooded hydrangeas in fall, you are cutting off next seasons blooms. Summer blooming hydrangeas, or those that bloom on new wood, are pruned in the fall, after they stop blooming.
With their vibrant, plump blooms, hydrangeas offer a striking display in the warm weather - but what do they look like in the winter? As the delicate petals fade in the colder months, bright hydrangeas can quickly appear dry and brown - requiring targeted care to get them flowering again in April.
The reason that climbing hydrangeas are pruned in summer is because the flowers are produced on the previous year's wood. If they are pruned earlier in spring, before flowering, the blooms for that year will be sacrificed.
So these shrubs should be pruned immediately after their flowers fade. Conversely, if the shrub flowers on new wood (stems developed during the current season), its buds are set within the season, so the shrub should be pruned in early spring before that new growth emerges.
When is Late Winter? Late winter is 4 to 6 weeks before spring thaw begins. This could be any time in January to May, depending on your climate.
Some introductions such as the Forever and Ever series or the well known Endless Summer family bloom both on old wood and new wood. The spring flowers occur on the prior year's old wood, while the fall flowers occur on the plant's current-season new-wood growth.
The period between the full and new moon (third and fourth quarters) is best for harvesting, slowing growth, etc.