Last updated on February 26th, 2022
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Hydrangeas are beautiful and rewarding shrubs to have in your garden. They are the quintessence of spring with their large blooms and overflowing growth. Knowing when and how to prune is important to keep these flowers blooming as much as possible. It’s also important to know that not all Hydrangeas should be pruned at the same time and pruning at the wrong time is could leave to your plant not flowering. It is actually one of the main causes of Hydrangeas not flowering. This is because some Hydrangeas flower on the previous year’s growth while others flower on the current year’s growth. So the trick here is to first know which type you have.
Most people have either the large Mophead Hydrangeas or Lacecap, both of which are easy to identify. Unless they are too big, they don’t really need pruning, however, pruning does encourage a much better display of flowers and sturdy plants. Simply cut back just under the flowers when they have faded, you can actually leave these on until after winter because they provide protection during the winter to the buds forming underneath. If you want to prune to reduce the size, cut back after flowering.
When to prune Hydrangeas
As I have just mentioned, knowing when the correct time to prune your Hydrangea is really contingent upon the type of Hydrangea that you have. The key is knowing whether your Hydrangea blooms on the wood from the previous season or from the current season. This is important to know so that you can prune around the development of upcoming flowers. You will know if you accidentally picked the wrong time because the upcoming season will produce no flowers.
Below are common pruning times based on plant type and is a good indication of the best time to prune:
|Common Names||Botanical Name||When to prune|
|Panicle Hydrangea||Hydrangea paniculata||Late winter|
|Bigleaf, mophead, lacecap Hydrangea||Hydrangea macrophylla||In summer, after blooms have appeared|
|Mountain Hydrangea||Hydrangea serrata||In summer, after blooms have appeared|
|Smooth Hydrangea, Annabelle, Snowball||Hydrangea arborescens||Late winter|
|Oak Leaf Hydrangea||Hydrangea quercifolia||In summer, after blooms have appeared|
|Climbing Hydrangea||Hydrangea anomala||In summer, after blooms have appeared|
You want to prune after the flowers begin to fade. This, more often than not, should take place at the end of summer. Shrubs that start to appear early in the summer or late spring and then diminish around the middle of summer are shrubs that produce flowers on the growth from old wood and as such it is important that you trim away earlier rather than later. This will allow your shrub more time to recover from its haircut and produce larger, more prolific blooms the following season. The most popular mophead Hydrangeas fall into this category and don’t need regular pruning other than to control the size, however, we do recommend cutting 2 or 3 old stems to ground level to encourage new growth followed by a light trimming after the flowers have faded.
If you are looking simply to tidy things up, you can maintain a well-manicured appearance in your garden by snipping away blooms that are spent after they have fulfilled their purpose and this is commonly known as deadheading. Cut them just below the flower head and then remove them. This will keep everything looking neat and tidy and prevent them from falling all over your garden. You can also remove any straggly canes all the way down to the soil line.
Removing old canes to improve the overall vigour
If your purpose is to improve the overall vigour and health of your plant you can remove the oldest canes. Once Hydrangeas get older and woody they start to produce smaller blooms. Regularly removing a few of the older canes all the way back to the soil level will allow your shrub to continue producing large and abundant flowers. The same thing can be said for keeping your shrub at an appropriate height. You can target the tallest canes in order to keep it from getting too tall.
Prune smooth Hydrangeas in the late winter or spring to ground level for the best show
If your goal is to generate incredibly large flowers the following season you can cut back your Hydrangeas all the way to the ground at the end of winter or the beginning of Spring. Smooth Hydrangeas will produce incredibly large blooms if you prune them like this every year, however, remember you shouldn’t do this with Hydrangeas that flower on the previous year’s growth.
Reduce the risk of Hydrangeas flopping over by pruning to a strong framework
In order to reduce the risk of Hydrangeas flopping, you can create a framework to support the plant. Larger Hydrangeas might fall over because of the sheer weight of their blooms, especially after it has rained and you can cut the stems to no more than a metre or so to provide a sturdy framework and that will help support the new growth and flowers as they bloom.