When to prune hydrangeas (and the bestselling variety to buy)
Hydrangeas are back in vogue, with new colours and varieties to choose from. Until not so long ago, they’d been more or less written off as unfashionable and old-school – an unwanted inheritance from a gardening era of lush lawns and island beds. Those large, blousy pink or blue pompom blooms harked back to our grandparents’ gardens. But much like dahlias and chrysanthemums, they’ve now been reclaimed as a must-have plant for contemporary gardens.
You can grow hydrangeas as single specimens, as a hedge, or in a mixed border for contrast with tall perennials and grasses. They are good as cut flowers too, both fresh and dried. Sarah Raven loves hydrangeas. ‘They are one of my absolute favourites,’ she tells House Beautiful. ‘They are fantastic for transforming otherwise dull spots into something full of life and colour, lighting up shady corners or the north-facing side of a house.’
And this is another key to their success: hydrangeas are a good plant for shady areas, and there's a variety to suit every style of garden. 'There are so many varieties of hydrangeas available, from traditional mop heads to lacecaps like macrophylla,' continues Sarah. 'I just love the elegant shrubby species like paniculata, arborescens, and aspera. Paniculata 'Limelight' is my all-round favourite hydrangea. The flowers open the cleanest, brightest, acid green.'
Whether you’re growing in the ground or in pots, hydrangeas add texture and colour with long-lasting flowers from June to October and often good autumn leaf colour too (even the spent flowers look great when left on plants over the winter months).
Discover more about growing hydrangeas, when to prune, and the best way to propagate for free, easy-to-grow beautiful blooms.
Hydrangea in a nutshell
Hydrangeas are medium to large-size deciduous shrubs with gorgeous summer blooms that also look spectacular as they fade over winter and lose their leaves. They are relatively easy to care for and many new varieties have been introduced with new colours and a longer flowering season. There also more compact sizes available with shrubby types or climbers to choose from – this makes them very versatile plants.
Where to plant hydrangeas
The ideal site is in part shade. This might be on the edge of a woodland area, with other shrubs to create a midstory under trees, or at the back of a mixed border providing a backdrop or contrast with taller upright or lower mounded plant forms. Depending on how much space you have, a grouping of three or more hydrangeas can look spectacular, but there are plenty more compact types to suit smaller gardens, balconies and terraces.
Avoid dry and south-facing sites as full sun can scorch the leaves, while deep shade may affect flowering. Sarah Raven advises: ‘Grow hydrangeas in moist, fertile soil in a partially shaded, cool part of the garden. Avoid east-facing sites, as cold winds can impact young spring growth.’
The best seasons to plant hydrangeas
Hydrangeas, which you’ll mostly buy in larger pot sizes, can be planted all year round. You’ll see the best results if planted in autumn or spring, when the ground is moist but not frozen or waterlogged.
Make sure to add plenty of organic matter to help retain moisture and encourage a strong root system to develop. Sarah advises checking the height and spread that your chosen hydrangea will grow to. 'Ensure you allow enough space for hydrangea plants to reach their full width, as plants from the aspera family can grow up to two and half metres! The deep root system of established plants should find moisture in summer, but water thoroughly once a week when faced with prolonged dry spells,' she explains.
When to prune hydrangeas
Good news: Hydrangeas don’t need rigorous pruning, but pruning them at the right time is key to maintaining their size, shape, and flower power. Generally, it’s best (and looks great too) to leave the faded flowers on the shrub throughout the winter months, as these give some frost protection to young shoots in early spring. For most types, light pruning in spring – late March or early April – to remove the dead flowerheads and thin out weak stems and reshape your shrub is all that’s required.
Pruning hydrangeas can also depend on the following:
Year-old stems that emerged over the previous season will carry the flowers, so you need to keep these.
For the arborescens and paniculata varieties, to encourage larger, but fewer flowers, cut back to two buds on the previous year's growth. Cutting back to four buds will produce medium-sized flowers.
With climbing hydrangeas, remove flowers after flowering and cut them back hard in spring to contain their growth; they will recover well, but don’t expect many flowers in the same year.
These are the most popular hydrangea varieties
The shrubby hydrangea types range from macrophyllas with large leaves and flowers that include the classic pink and blue varieties to the more compact H. serrata; the paniculata species which have longer, more pointed blooms; and arborescens, which have large flowers.
H. aspera (pictured) are large shrubs with softer, velvety leaves and clouds of dusky pink-purple lacecap flowers surrounded by white flowers. H. quercifolia is the oakleaf form, with large leaves that have great autumn colour too.
The climbers are H. anomala subsp. petiolaris and the evergreen H. seemannii, which is a great choice for sheltered urban spaces; and also the much smaller hydrangea scandens. Many of the popular new hybrids are a combination of scandens and macrophylla.
Shop hydrangea varieties at Crocus
But the bestseller is...
There are hundreds to choose from, with new varieties being introduced every year. However, as Roger Butler at Signature Hydrangeas, a specialist hydrangea nursery in Kent, says, old favourites like ‘Annabelle’ (pictured) continue to be one of the best sellers.
The first thing to consider is the size of your planting area and whether you have room for the larger shrubby types, or perhaps you need a petiolaris or seemannii to climb up a shady wall or fence? Then you can have fun thinking about the flower colour, which starts at the white and cream end of the spectrum, through to pale and deeper pinks, to blues and purples, with popular lime green colourings that are in demand at the moment.
Growing hydrangea in pots
Many of the newer, more compact types of hydrangea are ideal for growing in large containers. For example, Hydrangea arborescens ‘Ruby Annabelle’ is a pink variation of the full-size ‘Annabelle’ with large blooms from July to September that become yellow-green as the season progresses. Other smaller types ideal for pots include the newer paniculata varieties such as ‘Petite Lantern’, with flowers that change from white through to pink as they age, and ‘Little Quick Fire Fab’ and ‘Little Hottie’, available from Signature Hydrangeas.
Can you really change the colour of hydrangea blooms?
Hydrangea macrophylla varieties are the ones that famously respond to the change in soil pH, with pink flowers in alkaline soils, and blue in acid soils. The science behind this is down to the levels of aluminium sulphate that combine with anthrocynin in acid soil. If you buy a blue-flowering macrophylla, it will have been grown in acid compost and will only stay blue if your soil is truly acid. White flowering hydrangeas do not change colour with the soil.
Hydrangea cuttings
Already growing hydrangea in your garden? Add to your collection with free plants grown from cuttings. Most species can be easily propagated by taking cuttings in late summer. Simply cut non-flowering stems, trim the leaves, and cut just below a leaf node to leave it around six inches long. Reduce water loss by cutting the leaves in half and inserting each cutting into a pot of gritty compost.
Successful rooting takes around six weeks, and then you are ready to pot your cutting into a larger pot, keeping it sheltered over the winter months. The following spring, you can plant out healthy specimens or grow on in larger containers.
Pests and diseases to look out for
Hydrangeas qualify as pretty low maintenance and suffer from few pest and disease problems. However, they may succumb to fungal issues such as botrytis, rust, powdery mildew, and leaf spot. Most of these can be managed by good housekeeping: pruning plants to allow for good air circulation, removing any affected leaves as soon as they are spotted, burning them, and cleaning off your tools to prevent further spread.
Pests such as hydrangea scale can be unsightly but easily managed through encouraging predator insects or removing the affected parts of the plant.
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