When and how to deadhead hydrangeas – expert advice for these popular plants

Hydrangeas are some of the most beautiful garden shrubs with their blooms brightening up any garden with ease. But once the flowers start to fade, you may wonder what to do with them: should you cut them off, or leave them be?

Although not crucial, trimming the spent blooms from these flowering shrubs, otherwise known as deadheading, can have its benefits. 'Deadheading hydrangeas can help encourage new blooms on your plant and keep the hydrangea looking fresh and beautiful,' says Anna Eklöv, plant expert and founder of LÖV Flowers.

However, there are some dos and don'ts when carrying out this garden task – deadheading at the wrong time and in the wrong way can do more harm than good.

How to deadhead your hydrangeas

Unlike pruning hydrangeas, where you remove large parts of the plant to either shape or maintain the plant's size, or remove dead or diseased wood, deadheading involves only removing the spent flowers. By removing the dying blooms, you allow the plant to put its energy into root and bud development, rather than producing seeds. This, in turn, allows the plant to grow stronger.

Start with a pair of sharp pruning shears – such as these Gonicc ones from Amazon – and locate a dying or dead bloom. These are distinguishable by their faded, brown color and wilted appearance. 'Always use good, sharp secateurs which are disinfected regularly to prevent infection entering the cut stem,' advises Angela Slater, a gardening expert at Hayes Garden World. 

'To deadhead hydrangeas, take each flower that’s on its way out and follow the stem down to the next set of large leaves,' instructs Anna. You should see tiny buds in the crease between the stem and the leaf, she says. Cut the stem about half an inch above the new buds – removing these would stop them from developing into new flowers.

When to deadhead hydrangeas

‘Deadheading can be done either right after flowering, late winter at the end of the season, or early spring before the next season begins,’ says Rachel Crow, a garden expert from Homes & Gardens.

Deadheading your hydrangeas frequently throughout the growing season will keep the plant neat and preserve the plant's energy to create new blooms. 'If you can’t stand having the hydrangea looking past its best, all you need to do is cut off the spent blooms at the next pair of leaves down the stem,' says Angela.

However, in colder climates, it's worth keeping the final flush of flowers intact. You can deadhead throughout the blooming season, but stop deadheading the shrubs around mid to late fall, recommends Anna Eklöv of LÖV Flowers. By leaving these blooms in situ, they will help to protect the new buds beneath from winter frosts. Plus, they provide architectural interest to the winter garden.

In this case, Angela recommends that gardeners cut the heads off in late spring when there is less chance of a late sharp frost. If a cold snap is forecast when the heads have been cut off and the new shoots have appeared, just throw a sheet of horticultural fleece, an old net curtain, or an old sheet over the plant to protect the plants from frost, she adds.