In order to prune hydrangeas correctly, it is important to know which variety was planted. Depending on the cutting group, a slight pruning of the dead inflorescences is recommended or pruning to a third of the plant height.
How do I cut hydrangeas correctly?
To properly prune hydrangeas, you must identify the variety, as each variety has different pruning requirements. Generally they are divided into two cutting groups and cut in February. Remove dry inflorescences and shorten the shoots if necessary.
How to prune hydrangeas?
For hydrangeas that bloom on perennial wood (cutting group 1), old inflorescences can be carefully cut off. Pruning can be done in February. For hydrangeas that bloom on new wood (cutting group 2), old flowers can be cut back in late autumn and the shoots can be cut back by up to 2/3 in February.
Do hydrangeas need to be cut back?
For dense growth and lush flowers, all types of hydrangeas require regular pruning. However, caution is advised when it comes to intensity, as not all varieties may be rigorously shortened. The individual genera are therefore divided into two groups.
Section group 1
The inflorescences of these genera are already createdin the autumn of the previous year. It is therefore advisable to only cut back the speciesmoderately. If the flower buds that have already formed are removed, the flower will stop completely. New buds will not form until next fall.
If a larger pruning is necessary, for example because the plant is getting too big or needs to be rejuvenated, the cut is done in July. In the best case scenario, buds can still be created for next year. During a rejuvenation cut, a third of the branches are cut off close to the ground.
Conclusion: The plants can cope with more pruning, but the flowering could take longer than usual. Only carry out heavy pruning to rejuvenate or thin out older plants.
Types of cutting group 1:
- Farmer Hydrangea
- Plate hydrangea
- Serrata hydrangea
- Oakleaf Hydrangea
- Velvet hydrangea
- Giant leaf hydrangea
- Rough leaf hydrangea
- Climbing hydrangea
Tip
The farmer's hydrangea “Everbloom” blooms on new and old shoots. There is no “wrong” pruning with her – perfect for garden beginners!
Section group 2
This cutting group is categorized by the late bud formation. It only takes place in the year of flowering, so that more radical pruning is possible. The cut is done close to the ground, always above at least one new pair of buds. If this is cut off, the flower will fall out. If you want the hydrangea to grow larger, radical pruning is not necessary every year, but it encourages flowering.
Conclusion: A radical cut every year is possible, but not necessary.
Types of cutting group 2:
- Panicle hydrangea (exceptions: “Praecox” and “Dharuma”, treat like cutting group 1)
- Snowball hydrangea (e.g. Annabelle)
- Modern Farm Hydrangea (e.g. Endless Summer, The Bride)
Cutting hydrangeas in pots
Hydrangea needs annual pruning, even when cultivated in containers. Here too, pay attention to the respective variety to avoid the flower falling out.
Hydrangeas that are grown in pots also need annual pruning. Please note the instructions from the previous section. Depending on the variety, pruning can be a little more radical or very moderate. We have put together additional care instructions for container cultivation in this article.
When should hydrangeas be cut?
Pruning is generally recommended inearly spring. If the hydrangea is cut by February, flowering is guaranteed. A later cut can lead to a later onset of flowering.
Despite winter hardiness, frost can cause damage to freshly cut shoots and prevent wound healing. The old flower umbels act as frost protection, especially in the varieties of classic farmer's hydrangea and serrata hydrangea (cutting group 1). These hydrangeas form their flower buds for next year below the old flowers. When cutting, there is a risk of injuring the new, still invisible buds. And even if the buds are not injured during cutting, they are exposed to wind and weather over the winter. So wait until February to cut these varieties. (Source: hortensien.eu)
If you own a panicle hydrangea or a viburnum hydrangea such as the “Annabelle” variety (cutting group 2), you can safely remove inflorescences in late autumn, as the new buds do not form until spring. To be on the safe side, the shoots can only be pruned in February.
Pruning group 1: Flowering on two-year-old wood
Cutting group 1 forms its buds the year before flowering. Care must therefore be taken when pruning these types of hydrangeas in order to preserve the sprouts.
Ball hydrangea (farmer's, plate and serrata hydrangeas)
Flowering time
June to September
Cutting time
February
Instructions
As a rule, only the withered inflorescences of farmer's hydrangeas, plate hydrangeas and serrata hydrangeas should be removed. Pruning is done at the top pair of buds on each shoot. This form of trimming causes the volume to continually increase. To rejuvenate the plant, individual branches can be cut back to a height of 10 to 15 centimeters. However, these do not have any flowers in the year they are cut. New buds should form on the shoot in the following year.
Oakleaf hydrangea
Flowering time
July to August
Cutting time
February
Instructions
The oakleaf hydrangea naturally has extremely dense growth. Cutting off the dry umbels is generally sufficient. However, with increasing age, the individual shoots lose their flowering power. This manifests itself in the formation of fewer and rather weakly populated panicles. In this case, we recommend rejuvenating individual branches. For renewal, these are cut back to a maximum length of 15 centimeters.
Velvet, giant leaf and rough leaf hydrangea
Flowering time
July to August
Cutting time
February
Instructions
Just like the oak leaf hydrangea, the velvet, giant leaf and rough leaf hydrangeas are characterized by bushy growth. Cutting the frozen and withered plant parts is therefore enough. Cutting back individual branches to a height of ten centimeters can still be useful for rejuvenation or if the footprint is too small.
Climbing hydrangea
The climbing hydrangeas occupy aspecial positionin section group 1. As with the above-mentioned genera, the buds are formed on two-year-old wood, but pruning is usually donenotDue to the continuous prosperity in almost all directions, in principle no cuts are necessary.
If necessary, unsightly grown branches can still be trimmed in length. Due to the climbing hydrangea's moderate pruning tolerance, it can cope well with individual pruning. Based on the other species in cutting group 1, this should also take place between February and March. We have summarized additional tips and tricks for caring for climbing hydrangeas in your garden in this article.
Pruning group 2: Flowering on annual wood
Due to the formation of flowers on new shoots, old wood can be cut back without hesitation.
The hydrangea in the second cutting group are characterized by a significantly higher tolerance to cutting. Since the flowers are only formed on annual shoots, more radical pruning can also be carried out.
panicle hydrangea
Flowering time
August to September
Cutting time
Late autumn or February
Instructions
Due to the digestibility of pruning, larger cuts are also possible without any problem. Ideally, the individual shoots are shortened to a height of 1/3 of their original length. The intersection point should be just above a pair of buds or a resting eye. Regular pruning of the branches stimulates the branching of the panicle hydrangea, creating a dense shrub.
Note: By not pruning, even small specimens of Hydrangea paniculata develop into attractive bushes in just a few years. However, make sure to remove dead branches promptly, as these form an optimal basis for pathogens and pests. You can find an overview of the most common diseases here.
Snowball hydrangea (e.g. Annabelle)
Flowering time
June to September
Cutting time
Late autumn or February
Instructions
The snowball hydrangea becomes lazy to bloom over the years. Annual pruning is therefore recommended as this ensures continuous flowering. Just like the panicle hydrangea, the Hydrangea arborescens should be shortened by around 2/3. You should carry out a radical rejuvenation treatment on slow-flowering and old shoots. To do this, the individual branches are cut back to a height of ten centimeters. This promotes new growth and also strengthens the formation of new flowers.
Modern Farm Hydrangea “Endless Summer”
Flowering time
May to October
Cutting time
Late autumn or February
Instructions
Even if the varieties “Endless Summer” and “The Bride” are botanically classified as farmer’s hydrangeas, pruning differs in important ways. In order to enjoy the flowers for as long as possible, we recommend regularly trimming the dried inflorescences. In addition, the modern farmer's hydrangea can tolerate more pruning by around 2/3 of the shoot length. However, this does not have to take place annually and is particularly suitable if the plant or individual old shoots become lazy. The first thinning cut must only be made after five years of standing. As with the aforementioned species, the intersection point is a point above a pair of eyes or a bud. Even deep cuts down to a height of 10 to 15 centimeters can be handled without any problems.
Summary
The selected variety plays a crucial role in the correct pruning of the hydrangea. Depending on the genre and assignment to one of the two cutting groups, the intensity and timing vary. While cutting group 1 (farmer's hydrangea, plate hydrangea, serrata hydrangea, oak-leaf hydrangea, velvet hydrangea, giant-leaf hydrangea and rough-leaf hydrangea) includes all those species that bloom on two-year-old wood, cut group 2 (panicle hydrangea, viburnum hydrangea and modern farmer's hydrangea) includes the hydrangeas that bloom on one-year-old wood bloom.
For hydrangea in the first category, pruning is recommended in early spring between February and March. As a rule, only the dried parts of the plant are pruned. Radical pruning should only be done on shoots that are perennial and those that are lazy to flower, otherwise there is a risk that they will not bloom.
The hydrangeas in the second group are characterized by a very high cutting tolerance, so that cutting back to a height of 1/3 of the original length is unproblematic. Many varieties require regular pruning to form buds annually.
You can find a summary of individual cutting measures in this video:
The right cutting technique for hydrangeas
In addition to the right time, the correct cutting technique also plays a crucial role in ensuring optimal pruning. In addition to the height to be set, attention should also be paid to the cutting angle. Ideally, this is set slightly slanted and at an angle of 45 degrees. This means that any liquids that come out or emerge can flow away effortlessly. This primarily promotes wound closure and prevents the deposition of pathogens.
Each shoot must be examined individually to determine the correct height. The optimal intersection point is a few millimeters above the top pair of eyes or buds. A cut that is too close to the bud could damage it, preventing further sprouting. However, a distance that is too large hinders the growth of the buds and restricts them.
FAQ
How to prune hydrangeas?
The correct cutting technique is the be-all and end-all when caring for the wound areas and the further growth of the hydrangea. In practice, a cutting angle of 45 degrees has proven to be effective, allowing the flow of emerging and escaping liquids. In addition, the interface should be a few millimeters above the top pair of buds. A distance that is too large restricts the growth of the buds, a distance that is too small can lead to damage to the buds.
When should hydrangeas be cut back?
In principle, all cuttable hydrangea varieties can be cut back in early spring between February and March. The less frost-sensitive species of pruning group 2 (panicle hydrangea, viburnum hydrangea and modern farmer's hydrangea) can also be pruned in autumn between November and December if necessary.
What happens if hydrangeas are cut back too much?
The consequences of radical pruning are directly related to the variety planted. Hydrangeas in the first pruning group (farmer's hydrangea, plate hydrangea, serrata hydrangea, oakleaf hydrangea, velvet hydrangea, giant leaf hydrangea and roughleaf hydrangea) will respond to the heavy pruning with a lack of flowering. In contrast, such a cut promotes budding and flower formation in hydrangeas of the second cutting group (panicle hydrangea, viburnum hydrangea and modern farmer's hydrangea).
Can you cut back hydrangeas radically?
Basically, all hydrangeas can be radically cut back. However, for the species in the first cutting group (farmer's hydrangea, plate hydrangea, serrata hydrangea, oak leaf hydrangea, velvet hydrangea, giant leaf hydrangea and rough leaf hydrangea), this procedure is only recommended for perennial shoots that are slow to bloom. However, the shortened shoot will not bear any flowers the following summer. Genera of the second pruning group (panicle hydrangea, viburnum hydrangea and modern farmer's hydrangea) can be radically cut back annually to a minimum height of 10 centimeters without hesitation.
Which hydrangeas only have the flowers cut back?
In order not to endanger the buds that have already formed, only the spent shoot tips of hydrangeas in cutting group 1 (farmer's hydrangea, plate hydrangea, serrata hydrangea, oak leaf hydrangea, velvet hydrangea, giant leaf hydrangea and rough leaf hydrangea) should be cut off.
Are all hydrangeas cut back?
No, not all types of hydrangeas are cut back. The climbing hydrangea generally does not require any pruning due to its vine-like growth. Individual shoots can still be cut off if necessary if they have grown unsightly.