Pruning panicle hydrangea in winter

Hydrangea paniculata blooms late in summer on brand new wood. It's a fast growing big shrub, 8- to 10 feet tall.

Unfortunately, it's a bigger shrub than most people realize and so it's often planted in too small a space. (There are new "dwarf" varieties and we'll believe the size given on their labels just as soon as we see them stop growing!) Fortunately, with one simple pruning each spring any panicle hydrangea can be kept at half size.

You can cut a panicle hydrangea however you like, even right to the ground, during a winter thaw or early in spring. That year it will grow 3-, 4 or 5 feet and bloom on schedule. Or you can train it to a single trunk, call it a small tree, and cut the branches back to the top of the main trunk every spring. Either way the result is a plant that's smaller than it would be otherwise that is also full of lively new wood each year.

Here are some we cut each year because they can't be allowed to grow on to full size where they're placed. We cut them hard in early spring. The pictures tell the tale.

Tree form panicle hydrangea cut back and grown back

Shrub form panicle hydrangea cut back and grown back

Specifics of the clip

This is a Tip Cutting article, so it has related discussion at our Forum:

Prune to reduce old panicle hydrangea
Winter thaws, great time to prune

Panicle hydrangea (H. paniculata) is a summer blooming beauty, 8-10' tall and half again as wide. Left on its own in adequate space, as here, the gardener might just remove some old wood every year or two and otherwise just enjoy this low care star.

Panicle hydrangea (H. paniculata) is a summer blooming beauty, 8-10' tall and half again as wide. Left on its own in adequate space, as here, the gardener might just remove some old wood every year or two and otherwise just enjoy this low care star.

Pruning a tree form panicle hydrangea to keep it small

It's early spring, time to prune this tree-form panicle hydrangea to keep it from outgrowing its place. In addition, we'll avoid droopy bloom: New growth that would have come from the tips of last year's branches would have been spindly and likely to bend under the weight of the flowers.

It's early spring, time to prune this tree-form panicle hydrangea to keep it from outgrowing its place. In addition, we'll avoid droopy bloom: New growth that would have come from the tips of last year's branches would have been spindly and likely to bend under the weight of the flowers.

After pruning. Now, the shrub will not grow even larger than last year, as it would have. In addition, it will hold its flowers more erect than it would have if we had not pruned it. The improved flower support comes from branches that are thick and sturdy, springing as they will from near the trunk.

After pruning. Now, the shrub will not grow even larger than last year, as it would have. In addition, it will hold its flowers more erect than it would have if we had not pruned it. The improved flower support comes from branches that are thick and sturdy, springing as they will from near the trunk.

Here's that hydrangea in June...

Here's that hydrangea in June...

...and in August as it begins to bloom.

...and in August as it begins to bloom.

This particular tree hydrangea is not a great example of its species' form. Its canopy is unnaturally narrow as a result of crowding. The plant is in shade most of the day when it should have at least four hours of sun. It's also recovering from two years of even worse conditions while on hold in another area as utility construction took place in this area.

Yet it is a great example of the species' durable nature. Despite all, it still responds vigorously to pruning. What a trooper!

Two years and one transplant ago, the tree-form hydrangea we've just shown you had more room. However, it still couldn't be allowed to reach full size so we did keep it pruned.

Two years and one transplant ago, the tree-form hydrangea we've just shown you had more room. However, it still couldn't be allowed to reach full size so we did keep it pruned.

We cut it down to a trunk and stubs, like so, every spring.

We cut it down to a trunk and stubs, like so, every spring.

Pruning a shrubby panicle hydrangea to keep it small

In late winter or very early spring each year, we cut these shrubby panicle hydrangeas to keep them within bounds.

In late winter or very early spring each year, we cut these shrubby panicle hydrangeas to keep them within bounds.

We make a drastic cut because we know the shrubs will respond with about 4' of new growth.

We make a drastic cut because we know the shrubs will respond with about 4' of new growth.

Coming back strong, as expected: here they are in June.

Coming back strong, as expected: here they are in June.

And in August. You may notice that are some branches not blooming yet. That's normal for this late blooming variety 'Tardiva'. Its bloom continues into September.

And in August. You may notice that are some branches not blooming yet. That's normal for this late blooming variety 'Tardiva'. Its bloom continues into September.

A close look at the branch tips in August shows the developing flowers.

A close look at the branch tips in August shows the developing flowers.

The October display tells the whole bloomin' story.

The October display tells the whole bloomin' story.

Specifics of the clip

These shrubs had been pruned indiscriminately for about ten years before these pictures were taken. During that time they were simply sheared each time they seemed to be getting too big, sometimes several times in one year. This prevented some of the bloom, as branches cut in summer did not have enough growing time to produce flowers from their tips.

Additionally, branches at the base of the shrubs had been allowed to grow that crossed and inhibited each others' growth. In the photos below the shrubs are being pruned for the third time after that mistreatment. It's the final step of renovation -- removing 1/3 of the oldest wood each spring. It's also exactly what we'll do each spring from now on!

Each of these panicle hydrangeas is a collection of old gray wood and new red-brown branches.

Each of these panicle hydrangeas is a collection of old gray wood and new red-brown branches.

We are cutting the newest growth back to the base of the plant, and removing all the rest of the old canes that are poorly positioned.

We are cutting the newest growth back to the base of the plant, and removing all the rest of the old canes that are poorly positioned.

It may seem like this pruning is too drastic. It's not. Look again at the photos above -- they completely filled their space with the growth that developed from these few, short, well-spaced canes.

It may seem like this pruning is too drastic. It's not. Look again at the photos above -- they completely filled their space with the growth that developed from these few, short, well-spaced canes.

We work with hand clippers and curved-blade folding saws. To remove this old cane that was crossing and inhibiting the growth of two others, and do that without damaging the remainder, required several cuts at angles. Tough cuts, yet essential, as removing the entire stub was the only way to alleviate the problem.

We work with hand clippers and curved-blade folding saws. To remove this old cane that was crossing and inhibiting the growth of two others, and do that without damaging the remainder, required several cuts at angles. Tough cuts, yet essential, as removing the entire stub was the only way to alleviate the problem.

Janet is about to toss out one of the thick older canes she's just removed.

Janet is about to toss out one of the thick older canes she's just removed.

We cut to just beyond good sized buds on the branches. On branches we are cutting back to wood without buds, we're asking the plant to sprout new from dormant buds. Theree make a guess and cut to leave a stub large enough that it should produce hefty new buds.

We cut to just beyond good sized buds on the branches. On branches we are cutting back to wood without buds, we're asking the plant to sprout new from dormant buds. Theree make a guess and cut to leave a stub large enough that it should produce hefty new buds.

Smile time:

With Janet on this project you're seeing Chris Mahairas, an arborist with an interest in shrub pruning. He told us as we worked that he's especially fond of panicle hydrangeas. "There are so many of these in western Massachusetts where I grew up, I pretty much put myself through college on what I earned cutting and selling the flowers each summer."