When it comes to pruning Hydrangeas, all are not created equal. Some flower on old wood (last year’s growth), some flower on new wood and some flower on either. One thing that most do have in common is that they don’t need be pruned at all except when they become too large for their surroundings.
The first step in pruning Hydrangeas is knowing what you have. In most cases the specific cultivar isn’t that important. Most Hollies, for instance, can be pruned just about any time, whether it’s a Savannah, Foster, or Compacta. However, you risk losing your bright red berries if you prune a Nellie R. Stevens at the wrong time.
Similarly, different Hydrangeas have to be pruned at different times to make sure you don’t cut off the maturing buds. When it comes to pruning Hydrangeas, there are two different categories:
The Mophead (the flower looks like the name implies, the head of a mop or a softball) and the Lacecap are the two Hydrangeas that flower in pinks and blues. The Oakleaf Hydrangea has large leaves that look like, you guessed it, the leaf of an Oak, and has long, white cone-shaped flowers. These Hydrangeas bloom on “old wood”, meaning last season’s growth.
To be safe, these Hydrangeas should be pruned before August. This allows plenty of time to “age” and to set their blooms for next season. A simple rhyme to help you remember, but it doesn’t help with the white-flowering Oak Leaf Hydrangea:
“If it flowers in pink or blue, prune it before the Autumn hues”. So if you are pruning Hydrangeas that flower in pink or blue, we suggest pruning as their flowers begin to fade.
- Just to add a bit of confusion, forget all of this if you are pruning Hydrangeas called “Endless Summer”. Endless Summer Hydrangeas will bloom on old wood or new wood, but our standard procedure is to not prune them at all unless it has to be reduced in size.
Pruning Hydrangeas – PeeGee and Annabelle
PeeGee Hydrangeas and Annabelle Hydrangeas flower on new wood. These two cultivars have a very different look. Some of are even grown in tree form. They are less particular, but pruning at the wrong time will still have a negative impact on flower production of the PeeGee and the Annabelle.
As a general rule, common sense is your best defense when it comes to pruning Hydrangeas of this kind: DON’T prune them right before they flower…if you cut off the buds you cut off the flowers. If you want to be more precise, and you can remember the differences, the only time you really don’t want to prune the Annabelle Hydrangea is in spring and the only time you don’t want to prune the PeeGee is in the summer.
General Tips and Notes on Pruning Hydrangeas –
One of the most important parts of pruning Hydrangeas is pruning out the dead. This can be done at anytime of year. We prefer to do this as they begin to sprout new growth because it makes it easier to identify dead canes versus live ones.
After the plants are fully established, some people recommend pruning 25-30% of the canes down to the ground to encourage it to rejuvenate. We have a great deal of experience allowing the plant to grow at will with no restrictions on size. We also have experience pruning a portion of the plant to the ground every few years. Frankly, we don’t see a noticeable difference in the performance of one technique versus another. However, to reiterate, the most important aspect of pruning Hydrangeas is the ongoing process of pruning the dead canes out.
Make the distinction between “pruning” and “deadheading”. When we talk about pruning, we mean taking a foot or more off the plant. Deadheading is the process of cutting the spent flowers off the plant, not a substantial length of cane. Deadheading can be done at any time of the year.
Hydrangeas of all cultivars are great additions to any cut-flower arrangement. If you need long stem flowers, and you need to cut a lot of them, try following this pruning schedule. Cutting long stem flowers will have the same impact as pruning. If you are just cutting a few, don’t worry about it. Cut short stem flowers at any time.
The bottom line is this: pruning Hydrangeas of all cultivars is completely doable. If you prune a five-footer down to two feet, it will come back with a vengeance. You can also prune them at any time and you don’t sacrifice the plant, just the next cycle of flowers. However, frequent hard pruning Hydrangeas tends to leave the canes younger and weaker, causing them to sag more when flowers mature.
For a list of Hydrangea varieties, click here.
My Personal Gardener is a full-service landscape company in the Buckhead area of Atlanta. We are avid hand-pruners and shun the use of power shears. If you are interested in learning more about the work we do please contact us for a free evaluation and proposal.