Hydrangeas are one of the most loved shrubs in British gardens. Their big, bold blooms add colour and charm to any green space, and therein lies the challenge. Have you ever wondered why your hydrangeas do not bloom like they used to? Nine times out of ten, it isn’t the soil, or the weather. Frankly, most of the time it comes down to pruning.
Knowing how to prune hydrangeas is the key, you see. Properly pruned hydrangeas experience fresh growth and bring more blooms each year. Do it the wrong way, however, and it can leave you with bare stems and little to enjoy.
So, do you want to enjoy colourful hydrangeas once again? Great, then read along.
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How does pruning affect Hydrangeas’ health?
Regularly pruning your hydrangeas encourages better growth and larger blooms. You see, old stems often take up space and energy. When you remove them, it’s good because the plant puts more effort into fresh flowers. New shoots develop better and stronger where the old ones were.
So, pruning hydrangeas regularly is not just about neat looks. It actually keeps the shrub strong and full of life. That’s not the only reason, mind you. Pruning also stops the shrub from turning into a wild, tangled mess. Without a trim, branches cross and bend and you end up with a plant that has lost its natural shape.
Another big gain is health. Dead or damaged wood can spread disease. When you cut that away, you lower the risk and keep the plant free from rot and pests.
And now let’s ask the most logical question. What happens if you don’t prune? The blooms may shrink year after year. The plant may grow too heavy, flop, or even break under its own weight.
So, now you know why you should prune the plants, but…
When is best to cut back your hydrangeas in UK?
The best time to prune most hydrangeas is in late winter or spring. Exceptions to this rule are climbing hydrangeas, which you should prune in summer after they have finished flowering. Overall, there isn’t a specific month that works best for all types. We’ll explain why in a little bit.
But first, let’s establish that there is a difference between pruning and deadheading, so let’s clear that up.
- Deadheading – you just snip off old flowers that have faded. This keeps the plant tidy and stops it from wasting energy making seeds. You can do this anytime after the flowers fade.
- Pruning – you cut back stems and branches to shape the plant, remove old or damaged wood, and help new growth. This is more serious than deadheading and affects how the plant grows next year.
Now that you know the differences, it’s also important to know that different types of hydrangeas have different pruning times. Hydrangeas fall into two main groups: those that flower on old wood and those that flower on new wood. The best month to prune depends on the type of hydrangea you have.
When to cut old wood bloomers?
These make flowers on last year’s stems. Prune just after flowering in mid to late summer. If you cut them back too early, you remove the buds, which means there will be no flowers later. Some plants which fall into this category are:
- Bigleaf hydrangea (Hydrangea macrophylla)
- Oakleaf hydrangea (Hydrangea quercifolia)
- Climbing hydrangea (Hydrangea petiolaris)
When to prune new wood bloomers?
These form buds on fresh stems each year. You can prune these hard and you won’t lose blooms. Cut them back in late winter to early spring before new growth starts. Some examples include:
- Panicle hydrangea (Hydrangea paniculata)
- Smooth hydrangea (Hydrangea arborescens)
- PeeGee hydrangea (Hydrangea paniculata ‘Grandiflora’)
- Limelight hydrangea (Hydrangea paniculata ‘Limelight’)
Now that you know the most popular plants, you can easily answer “How do I know what type of hydrangea I have?”. If your hydrangea blooms early in summer on stems that grew the year before, it’s an old wood bloomer.
How to be sure your hydrangea needs pruning
Look closely at your shrub and check for overgrowth. If stems cross, bend, or make the plant messy, it needs a prune. Examine the branches for dead, damaged, or diseased wood. Remove these stems to keep the plant healthy and stop problems from spreading.
Observe the flowers. If blooms look small, sparse, or lacklustre, the shrub may need pruning or hard pruning to produce stronger growth. Watch for weak, spindly, or crowded stems, and flowers hidden under leaves.
By following these signs and acting at the right time, you can decide when to hard prune hydrangeas, keeping your plants healthy and full of vibrant flowers.
How to cut hydrangeas without damaging them?
Before you learn how to prune your hydrangeas, equip yourself with:
- Sharp pruners – for small stems and precise cuts.
- Loppers – for thicker branches or overgrown areas.
- Gloves – to protect your hands from scratches and sap.
- Disinfectant spray – clean your tools before and after to stop disease from spreading.
Mind you, you can cut all the way back only new wood bloomers. Old wood bloomers should never be cut all the way back, or you will lose next year’s flowers. Also, always under-prune rather than over-prune, especially with old wood bloomers. Over-pruning can remove flower buds or weaken the plant.
Pruning old wood hydrangeas
- Deadhead faded flowers just below the bloom to tidy the plant.
- Remove dead, diseased, or crossing stems to improve air circulation and health.
- Cut back up to one-third of the oldest stems at ground level to encourage renewal
Pruning new wood hydrangeas
- Cut stems back to about 30–45 cm (12–18 inches) from the ground.
- Leave several strong stems to support fresh growth and flowers.
- Shape the plant lightly to maintain balance and an attractive form.
- Aggressive pruning is safe, as new wood bloomers produce flowers on current year’s growth.
What to be careful about when pruning?
A few mistakes can seriously harm the plant. Such as:
- Over-pruning – Cutting too much weakens the plant and reduces flowers next year, as you already know.
- Leaving dead or diseased wood – This can spread disease and pests.
- Pruning at the wrong time – Avoid heavy pruning in the fall. You can remove dead or diseased stems, but pruning old wood bloomers will remove next year’s buds.
- Using blunt or dirty tools – This can crush stems or spread disease.
Do your pruning right and at the right time and your hydrangeas can last 30 to 50 years.
Hydrangea care tips for healthy growth
Pruning is only part of keeping hydrangeas happy. A few simple care steps make a big difference.
- Mulch after pruning – Add a layer of compost or bark around the base. This keeps soil moist and stops weeds from taking over.
- Fertilise in spring – A balanced fertiliser gives nutrients for strong stems and bigger flowers. Avoid too much nitrogen, or the plant will grow leaves instead of blooms.
- Check for pests and diseases – Look for spots, mildew, or insects. Catching problems early keeps the shrub healthy all season.
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Takeaways
- Pruning is the key to keeping your hydrangeas healthy.
- Hydrangeas fall into two groups – old wood bloomers and new wood bloomers. Each type has its own pruning times.
- Signs your hydrangea needs pruning include overgrowth, crossing stems and weak or spindly growth
- Common mistakes include over-pruning, doing it at the wrong time and using blunt tools.
- After you prune, mulch, fertilise in spring, and check for pests.
