In this article I show you how to prune hydrangeas, with a simple step by step process.
There are multiple species of hydrangea and many different varieties or cultivars within each species. This means, it is pretty easy to find a hydrangea to suit your garden.
Hydrangea flowers
Hydrangeas are grown for their showy flowers. When we prune hydrangeas, it is generally so as to ensure that we get the best flower displays each summer. Therefore it is important to understand all about hydrangea flowers before we learn about the pruning techniques.
Hydrangea species tend to have flowers of different shapes. This is one of the distinguishing features. Thus:
- Hydrangea microphylla (hortensia) or Hydrangea arborescens have round ‘mophead’ flowers;
- Hydrangea microphylla, Hydrangea serrata, Hydrangea villosa or Hydrangea aspera have ‘lacecap’ cultivars, which have flatter flower heads with mini flowers in the centre and larger flowers on the outside, and
- Hydrangea paniculata or Hydrangea quercifolia have cone-shaped flowers.
One of the other distinguishing features of hydrangeas is their flower colours. We typically see pink, blue, mauve, white or green flower colours on hydrangeas. The pink/blue cultivars tend to have blue flowers where the soil is acidic, pink flowers where the soil is alkaline and mauve flowers where the soil is neutral.
Flower colours of hydrangeas also change over the growing season – white flowers frequently turn pink and blue and pink flowers often fade to shades of green and red.
In fact, what we think of as the flower petals on hydrangeas are actually sepals – outer bracts that protect tiny flowers within. It is the sepals that are coloured and therefore the primary feature of hydrangea blooms.
Another important point to remember is that most of the flowers on most hydrangeas are sterile and therefore don’t produce seeds. On mophead hydrangeas, there are a few fertile seed-bearing flowers in the centre of the bloom, but most of the flowers are sterile. On lacecaps there are more fertile flowers. These are the small inner flowers. The larger outside flowers are sterile.
How to prune Hydrangeas – step by step
There are some variations in how to prune hydrangeas according to the different species. Steps 1 to 4 below apply to mophead and lacecap hydrangeas. Other species are covered in Steps 5 and 6.
Total Time: 15 minutes
Understand how hydrangeas flower
The important point to remember is that hydrangeas flower on shoots that extend from the previous year’s growth. So if you cut hydrangea stems back too hard you will lose the next season’s flowers.
Timing
It is generally best to prune mophead and lacecap hydrangeas in late winter or early spring. It is a good idea to leave the spent flower heads on the plant over winter as this tends to protect the buds of the flowering shoots that are developing lower down on the stem.
Lacecaps are a little bit hardier, so if preferred their blooms can be removed after flowering. But many people prefer to leave all the dead flower heads on the plant over winter as they provide more visual interest that than the bare stems.
Cut out dead or congested stems
Before you cut back the dead flowers in late winter or early spring, it is best cut back any dead stems right to the base. It is also a good idea to take out 1 or 2 stems from the centre of the bush each year to let in more light and encourage fresh growth that will flower in the years to come.
If a specimen is old or very congested, you can cut all the stems back hard to regenerate the whole bush. But be aware, there won’t be any flowers that year. Instead flowers will come the following year on the current year’s growth.
Remove spent flower heads
After you have thinned out the shrub a little, you can remove the spent flowers. Cut the stems just above a pair of healthy buds.
As the buds begin to break, feed the plant with a balanced fertiliser and mulch it well. This should encourage the new shoots to grow away strongly. 
Hydrangea paniculata and Hydrangea arborescens
Hydrangea paniculata and Hydrangea arborescens flower better if given a slightly more vigorous pruning. So, as well as removing any dead or damaged stems, you should prune these back to the lowest pair of healthy buds in spring. Do this across the whole plant, creating a framework of stems 2-3 feet high (30 to 60 cm). This should produce strong healthy branches and large flower panicles.
Climbing hydrangea – Hydrangea anomala subsp. petiolaris
Flowers on the climbing hydrangea mainly appear at the top of the plant, so it is best to leave as much of this unpruned as you can. However, prune back any unruly shoots you do want to remove immediately after flowering.
Conclusion
Follow these steps when pruning your hydrangeas, especially giving them a good feed and mulch at the start of the growing season and you should find you are rewarded with strong healthy plants and beautiful flowers.
What you need
All you really need are a good pair of secateurs. I always use Felco Number 2 secateurs which I have always found to be the best secateurs for any pruning job.
US Buyers
UK Buyers
Felco Professional Model 2 Secateur
- comfortable lightweight, easy to grip handles,
- a hardened steel blade with a wire cutting notch,
- riveted anvil with sap groove to allow plant fluids to drain away
- a toothed centre nut mechanism which easily aligns the blades for a clean precise cut
- a rubber cushion shock absorber that protects the wrists.
Felco No 2s carry a lifetime guarantee and all parts can be replaced, so it is easy to see why these are the secateurs of choice for many horticulturists and serious home gardeners.
21.5cm/8.5" overall length can cut stems up to 2.5cm/1" in diameter.
Weight 240g/8.5oz
Felco Leather Secateur Holster
Buy Hydrangeas
US Buyers
Annabelle Hydrangea
Fire Light Hydrangea
Little Quick Fire Hydrangea
Pinky Winky Hydrangea
Limelight Hydrangea
UK Buyers
Hydrangea paniculata 'Pinky Winky
Hydrangea arborescens 'Strong Annabelle
Hydrangea macrophylla 'Endless Summer - Bloomstar
Hydrangea macrophylla 'Blue Danube
Martin Cole has been an avid plant lover and gardener for more than 20 years and loves to talk and write about gardening. In 2006 he was a finalist in the BBC Gardener of the Year competition. He is a member of the National dahlia Society.
He previously lived in London and Sydney, Australia, where he took a diploma course in Horticultural studies and is now based in North Berwick in Scotland. He founded GardeningStepbyStep.com in 2012. The website is aimed at everybody who loves plants or has been bitten by the gardening bug and wants to know more.
Gardening Step by Step has been cited by Thompson and Morgan, the UK’s largest mail order plant retailer, as a website that publishes expert gardening content.