How to Prune Hydrangeas
One of the most common questions we get asked about hydrangeas is about pruning - when and how to prune.
The first step to pruning your hydrangea is to identify which type of hydrangea you have. This is very important to know before you prune because this will tell you whether to prune in the spring or fall. Some hydrangeas form their flower buds on old wood, meaning next year's buds are already present on the branches in the fall and winter. Other hydrangeas form their flower buds on new wood once they begin to grow in the spring. It is only recommended to prune hydrangeas that bloom on new wood in the fall without the risk of sacrificing next year's flowers.
Once you have completed step 1 and identified which type of hydrangea you have (this step should be fairly simple - if the hydrangea is new you probably still have the tag, you can come back to Garry's Garden Gallery and match up your hydrangea with ours or ask our greenhouse experts, and the internet is a great source for answers too)
Most of your hydrangeas that bloom on old wood should be pruned as soon as they are finished flowering except hydrangeas that bloom on old wood finish flowering so late in the season that pruning right after they bloom does not leave enough time for them to regrow and form the flower buds for next year. So it is best to avoid pruning this type of hydrangea except to remove completely dead branches in the spring time once the plant starts to leaf out.
Hydrangeas that bloom on new wood can be safely pruned in the late fall once the hydrangea has gone into dormancy or in the early spring. The flower buds will not form until late spring the same year that they bloom so there isn't risk of you removing the buds. Some people like to leave the blooms on the plants for the winter as they like the look of the dried hydrangea flowers over the winter. Some people like to have them pruned for the winter so they look tidier, especially if you live where you get a heavy snow load that is just going to weigh them down.
We haven't talked about reblooming hydrangeas yet. They produce flowers on both old and new wood. This can make it confusing as to when the best time to prune is so that you don't sacrifice some flowers. The best way to prune these hydrangeas is the same way as the hydrangeas that bloom on old wood meaning you should only have to remove the completely dead branches in the spring once the plant starts to leaf out.
The final step to pruning your hydrangea is knowing how much you can safely prune off. Generally, it is alright to prune up to one third of your hydrangea that blooms on new wood. For example if your hydrangea is six feet tall then you can prune two feet off the top and sides. You don't want to prune more because you will remove too much of the sturdy framework that keeps your plant standing tall and because your plant needs to keep enough of its foliage to make an adequate amount of food to support the root system.
When you are doing your pruning, make your cut just above a set of healthy, big leaves. Remember if the branch is completely dead you can cut it right out but if you are in doubt, don't cut it! Do not prune your hydrangeas throughout the growing season or you risk cutting off the flower buds. You can't just keep pruning your hydrangea to keep it small. It will grow back to it's original size or even larger as the pruning stimulates new growth. If your hydrangea turns out to be too big for where you have it planted then you can transplant it when it is dormant to a new spot in the early spring and plant a smaller variety in the original place.
Head into Garry's Garden Gallery for expert advice on which hydrangea is best for you!