Wilson Bros Gardens LLC

Unlike older varieties of Hydrangea macrophylla, which produce their flower buds on old growth (the previous years stems), Endless Summer hydrangeas produce buds on both old and new growth, which is why they bloom during the entire growing season when new growth is being produced, hence the name 'Endless Summer'. 

Because they have such a long bloom period that starts with the first cycle of blooms in late spring, which open from the buds produced late in the season last year, and continue to produce buds and blooms throughout the summer, I'm often asked "when is the best time to prune my Endless Summer Hydrangeas?" Endless Summer Hydrangeas don't require any pruning. That said, they are very forgiving and will not suffer if pruned any time of year. 

(1-5 years old) 

It's best to leave young Endless Summer Hydrangeas alone for the first 4 to 5 years. That said, removing damaged or dead branches as they appear, and deadheading spent flower clusters throughout the growing season, will encourage new growth, which means more buds and flowers. When deadheading, cut the stem at a 30 degree angle at a point just above the first set of leaves beneath the spent flower.

(4 years or older) 

When Endless Summer Hydrangeas have matured (4 years or older) I give them an annual pruning in early spring, when new leaves start to emerge along the stems. This way I can identify any dead stems. At this time, I cut back any damaged or dead branches to the ground. Then I remove about 1/3 of the old, darker stems by cutting them back to the ground.  

After the first flush of flower clusters have faded in summer on your Endless Summer Hydrangeas, it's a good idea to deadhead them all. This encourages an abundant second flush of flowers. When deadheading spent flowers, cut the stem just above the first set of leaves beneath the spent flower at approximately a thirty degree angle.

Fresh or spent flower clusters can be cut any time.

Hydrangea macrophylla, commonly called mopheads or French hydrangeas, are those that produce the large leaves and large, snowball-like flower clusters in shades of blue, pink, white or red during summer. With the exception of the Endless Summer and other ever-blooming H. macophylla, most of the older mophead varieties bloom only on old wood, which means the flowers produced during the current year come from buds that were produced the previous summer or fall. 

Mophead hydrangeas don't ever have to be pruned. That said, older shrubs (5 years or older) can benefit from an annual pruning in early spring, when new leaves begin to emerge. This way you can see which stems are dead or alive. Start by cutting any damaged or dead stems back to the ground. Then remove about 1/3 of the old, darker color (living) stems by cutting them down to the ground. 

Fresh or spent flower clusters can be cut any time. When flower clusters have faded, you can deadhead them. When deadheading spent flowers, cut the stem at about a 30 degree angle just above the first set of leaves beneath the spent flower. Before August, you can cut flowers off with long or short stems without effecting next years bloom. After August, you want to be careful to cut stems very short. As long as you cut above the first set of large leaves, the buds will be fine. 

Hydrangea serrata, commonly called lacecaps because of their flat flower clusters, are very similar to H. macrophylla (mopheads), but the leaves and flowers are smaller.  

Even mature Lacecap hydrangeas require little to no pruning. That said, if mature shrubs become overgrown you can cut back stems by about one-third their height right after the blooms have faded in summer, before August. If shrubs are not overgrown, you can remove about a third of the old, darker color branches by cutting them down at ground level. Keep in mind that if you wait to long to cut stems back (after August) there's a risk of removing newly formed buds that would be next years flowers.

Pruning oakleaf hydrangea varieties is simple: don't do it, except to remove damaged or dead branches as they appear. That said, if and when there comes a need to prune to reduce size or for aesthetic shaping, pruning of oakleaf hydrangeas is best done in late summer or early fall, at any time after the plant has finished blooming. Oakleaf hydrangea can be pruned in spring, but know there is the risk of losing flower buds. 

Hydrangea paniculata, commonly called pee gee hydrangeas, do not require pruning. They can be left unpruned indefinitely, except to remove damaged or dead branches as they appear. Any pruning is merely done to limit size or for aesthetic shaping by removing stray, broken, dead or crossing branches. 

Pee gees bloom on new wood (current seasons growth). So, if you want to prune them to reduce size or for shaping purposes, avoid doing so when they are preparing to bloom in summer as this will effect flowering. Pruning is best done in late winter or in summer or early fall after the plant has finished blooming.  

Pee gees are the only hydrangeas that can be pruned into a tree-form. To tree-form, in late winter, simply remove lower branches by cutting them as close as possible to a trunk. If there are more trunks than you like, these can be removed as well by cutting them to the ground. Just be careful to notice how the removal of a trunk will effect the canopy.

Hydrangea arborescens, commonly called smooth hydrangeas, such as 'Annabelle', can be left unpruned indefinitely. They bloom on new wood (current seasons growth), so avoid pruning these them when they are preparing to bloom in summer as this will effect flowering. Any pruning is merely done to limit size or for aesthetic shaping by removing stray, broken, dead or crossing branches. Pruning is best done in summer or early fall after the plant has finished blooming, or in late winter before new growth begins to emerge.