Confused about when to prune hydrangeas? Pruning hydrangeas at the correct time is so important. When, you prune your hydrangeas can make the difference between beautiful giant flowers or none at all.
About half the pruning questions googled are related to hydrangeas.
Do it yourselfers all fear the same thing: Incorrect pruning will lead to a hydrangea that doesn’t bloom. And if your hydrangea doesn’t bloom, then what’s the point of having them.
The confusion is caused because some hydrangeas bloom on new wood, meaning the current seasons growth, while others bloom on old wood, which is last seasons growth.
Adding to the frustration is the fact that in colder climates old wood hydrangeas can fail you, even when you follow the old wood pruning rules.
Hydrangeas That Bloom On New Wood
When a hydrangea blooms on ‘new wood’, it means that flowers bloom on flower buds that were formed that season. These flower buds weren’t there during the winter months. Instead they were formed when the hydrangea started putting on new growth in the spring.
Pruning new wood hydrangeas should be done in late winter or early spring, before the plant starts to put on new growth.
You have a couple of choices to make when it comes to pruning new wood hydrangeas. Sometimes you’ll want to cut the plant back to within a couple inches of the ground. While other times you don’t want to cut it back to more then 1/3 its size. So how do you know which method to use?
It really comes down to which type of new wood hydrangea you have. New wood hydrangeas are either Annabelle’s, or Panicles.
- Annabelle hydrangeas should be pruned fairly close to the ground. In fact you can prune them all the way to the ground but it’s best to leave several inches of last years wood to create a support structure for new growth. This will prevent the floppiness you sometimes see from Annabelle Hydrangeas.
For help identifying Anabelle Hydrangeas, check out this link: Annabelle Hydrangea Identification
- If you have Panicle Hydrangeas you don’t want to cut them back as severely. Instead, they should be cut back no more then 1/3 of its size in late winter/early spring.
Panicle Hydrangeas are very cold hardy and are a great choice for colder climates (zone 5 or less).
For help identifying Panicle Hydrangeas, check out this link: Panicle Hydrangea Identification
Hydrangeas That Bloom On Old Wood
When a Hydrangea blooms on ‘old wood’, it forms its flower buds shortly after blooms fade in summer. This means that the flower buds and stems of the plant have to survive the winter for you to get blooms next spring/summer. If you’re in a warmer climate, this usually isn’t a problem.
If you’re in a colder climate, this is much harder. Cold winters can cause your hydrangea to die back.
In early spring you’ll be left with a bunch of dead branches that need to be trimmed way back. For this reason, if you’re in a colder climate, it’s best to avoid planting hydrangeas that bloom on old wood.
When pruning old wood hydrangeas you have to be very careful with your timing. You want to prune when your hydrangea is just about done blooming for the year. Don’t wait too long. Shortly after blooms fade your hydrangea will start to develop next years flower buds. Pruning too late in the season would mean pruning off next years flowers!
Selective pruning is another type of pruning that applies to both new wood and old wood hydrangea.
This means using a pair of bypass pruners and selectively cutting out branches that are dead, diseased or old, or spent flowers. You can also cut branches that are crossing each other or rubbing against each other.
Do You Have to Prune Hydrangeas?
Make it easy on yourself. If there’s no reason to prune your hydrangeas then don’t do it. The benefits of pruning are shaping the plant, and maintaining size and vigor. If you are happy with the shape, size, and health of your plant then feel free to leave your hydrangea untouched.
Why Are My Hydrangeas Not Blooming?
There are 5 main reasons why your hydrangeas aren’t blooming:
- Having old wood hydrangeas in a colder climate where they die back during harsh winters.
- Pruning old wood hydrangeas after the flower buds have developed.
- Plant is not mature enough.
- Not enough sun for Panicle hydrangeas. Panicle hydrangeas bloom best with 4-5 hours of sun. However If in southern zones avoid afternoon sun exposure.
- Deer have eaten flower buds.
Hydrangeas That Bloom on New and Old wood
Want to make things really easy? There are a few hydrangeas that bloom on both new wood and old wood. These include Endless Summer Hydrangea, as well as Proven Winners ‘Lets Dance’, and ‘Tuff Stuff’. Planting these varieties makes it a lot easier to avoid pruning mistakes.
Hydrangea Identification Help
If your hydrangeas are in bloom then identification is much easier. Check out this quick video, and you will be able to see what kind of hydrangea you have: Hydrangea Identification
If it’s late winter or early spring and your hydrangeas aren’t in bloom then identification is much harder.
Say you just moved into a new home, or maybe you haven’t paid much attention to your hydrangeas before. You may have no idea if you have and old wood hydrangea or a new wood. There’s no need to worry. The best thing you can do is wait!
Wait until late spring or early summer (or earlier depending on location) when hydrangeas are starting to put on new growth, and leaves have developed. By then you should be able to use the leaves for identification. This is a great site for identifying hydrangeas by leaves (leaf identification is towards bottom of the post): Hydrangea Leaf Identification.
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