How to prune hydrangea: a step-by-step guide

How to prune hydrangea: a step-by-step guide

the summery of project

work time: 15 to 30 minutes
Total time: 15 to 30 minutes
Skill level: Beginner
the expected cost: $20 to $28

Before you start

Keep in mind that there are other articles on drying hydrangeas, growing hydrangeas in pots, fertilizing hydrangeas, and changing hydrangea color. This will focus solely on pruning hydrangeas. Before you begin, clean your shears with a disinfectant solution like Lysol and select the best cut for the species you have.

Photo: istockphoto.com
  • Old woodSpecies that thrive on old wood include the most popular large-leaved hydrangea (Hydrangea macrophylla(and also oak leaves)Hydrangea quercifolia), rough paper (Hydrangea Aspira), and ascension (Hydrangea petularis) Hydrangea varieties.
  • New woodSnowball shrubs that flower on new wood include hydrangeas (Hydrangea paniculata) and soft hydrangea (Hydrangea bushes).
  • Re-prosperity: Repeat-blooming varieties such as the Endless Summer Series thrive on both old and new wood and should be treated like older wood species for a continuous flower display.

RELATED: 20 Outdoor Plants You Can Propagate Through Cuttings

How to prune hydrangeas that bloom on old wood

If you're debating when to prune hydrangeas that bloom on old wood, such as large-leafed and oak-leafed species, do so right after they finish flowering. If it blooms in June in your climate, for example, prune it in early July. Do not delay pruning hydrangeas until August or you may cut off new buds that are already starting to form for the following year.

Step 1: Kill any wilted flowers remaining on the hydrangea bush.

Cut back the hydrangea bush or prune it with garden shears.  High quality image
Photo: istockphoto.com

Removing dead hydrangea simply means removing faded flower heads by cutting them off. Do this by using bypass pruning shears to cut each stem below the flower head and just above the nearest pair of leaves below it. For lace types, cut off the second pair of leaves to help prevent seed formation.

If you like the look of old flower heads, you can leave them on the plant, especially for oak-leaf types, as the flowers gradually darken to pink and then purple before drying out completely.

Step 2: Remove branches that appear dead, worn out, or tend to rub.

Cut back the hydrangea bush or prune it with garden shears.  High quality image
Photo: istockphoto.com

Trim branches that have become brittle and show no foliage or green pulp when scraped. Cut them back to the point where you see the green pith inside or – for branches that show no green at all – remove them completely.

When two branches rub against each other, cut the weaker (smaller) one to prevent it from damaging the other; For these green branches, use bypass shears if you can. Finally, remove about a third of the oldest stems from the plant.

Step 3: Cut the hydrangea bush back to your preferred size.

Cut back the hydrangea bush or prune it with garden shears.  High quality image
Photo: istockphoto.com

If the shrub becomes too large for its location, cut it back to your desired size, making each cut about 1/4 inch above a pair of leaves. However, this is unlikely to subdue it for long. As University of California Master Gardener Norm Phillips notes, “The plant usually immediately returns to its previous size. This is why it is best to plant hydrangeas in a location where they have enough room to grow.

Climbing Hydrangea: Treat climbing hydrangeas as you would other old woody bloomers.

Climbing hydrangea blooms on old wood, i.e. side shoots from the previous year. However, it generally doesn't require any pruning other than removing dead branches and vines that have strayed farther than you'd like.

Deadwood can be cut back at any time but wait until this climber has flowered in late spring or early summer to cut off live vines. The Royal Horticultural Society notes that “most flowers appear towards the top of the plant, so try to leave as much of these flowers unpruned as possible.”

Hydrangea petularis in bloom.  Young green leaves of Hydrangea petularis in summer.  Climbing hydrangea.
Photo: istockphoto.com

Related: 14 Best Shrubs for the Front of a House

How to prune hydrangeas that bloom on new wood

Are you wondering when you should cut back hydrangeas that bloom on new wood like the smooth and cluster types? Choose early spring after new leaf buds begin to appear, so you can identify which branches are still alive. Prune them moderately if you prefer large shrubs with an abundance of small flower heads. If you prefer small shrubs with large but fewer flower heads, opt for more stringent pruning.

Step 1: Cut the shoots by one-third to one-half.

Hydrangea pruning
Photo: istockphoto..com

For the first option, remove a third to a half of each shoot, cutting 1/4 inch above a pair of leaf buds each time. The exception, of course, is dead or partially dead shoots, which should be cut completely back or back to where the leaf buds appear. Always use bypass shears when you can, since anvil types sometimes crush what they're supposed to cut, which can cause more harm than good.

Step 2: Alternatively, cut the shrub back to a height of 1 foot.

Pruning bushes closely.  Pruning a hydrangea bush.
Photo: istockphoto.com

For the second option, which generally applies only to smooth species (trees) that have been allowed to grow for a few years, cut back the entire shrub hard. Cut each shoot about 1 foot above the ground, cutting them just above the leaf buds as mentioned above.

Do not repeat this type of severe pruning too often as it may eventually weaken the shrub. The large flower heads they produce may also require stacking to help them keep their heads up.

Step 3: Remove weak shoots, leaving only the larger ones in place.

Close-up of hands wearing work gloves clearing the ground of dry grass and leaves around a hydrangea growing on wet ground in the garden in broad daylight.  An outdoor recreational activity for nature lovers who live in the countryside.
Photo: istockphoto.com

Whichever alternative you choose, once you have made the initial cut, examine the remaining shoots. If any of them rub against each other, remove the smaller, weaker ones. In fact, it is a good idea to remove any buds that are clearly inferior to the others, allowing the remaining stronger buds to become stronger. Long-handled shears, rather than pruning shears, will help you reach the center of the shrub, but are only necessary to cut any branch larger than 3/4 inch in diameter.

Final thoughts

If you follow the tips above, you should be able to prune your hydrangeas without sacrificing the flower buds. However, if you're having a hard time understanding the concept of old wood versus new wood, you may want to play it safe and avoid pruning those shrubs at all.

After all, if they have a lot of space, it's not really necessary for you to cut them down. As the University of Maryland Extension says, “A safe rule for all hydrangeas is better than no pruning than the wrong kind of pruning.”

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