What to do with hydrangeas in October to set your plants up for winter and give next year's blooms a head start

When it comes to hydrangeas, what’s not to love? With their blousy blooms, vibrant colours and long flowering period, these easy-care shrubs make a fabulous addition to any garden. And even with this year’s long, hot summer, my hydrangeas survived the heat and are still bringing some autumnal colour to my garden even now. But as the blooms start to fade, the question of what to do with hydrangeas in October arises, and I’m never quite sure whether I should be cutting back or leaving them alone when it comes to autumn hydrangea care…a question I put to the gardening experts.

‘With hydrangeas putting on their final display of the year, October is the ideal time to start preparing them for the colder months ahead,’ says Shelley Davis, plant expert at Flying Flowers. ‘But knowing what to cut back, what to leave alone, and how best to protect the plant can make all the difference when growing hydrangeas.’

Find out exactly what you should be doing to get your hydrangeas prepped for winter with our expert-approved tips below.

1. Don’t rush to prune hydrangeas in autumn

‘It might feel like the time to get the pruning shears out, but it’s worth holding off before cutting everything back,’ advises Shelley. ‘If your plant has finished flowering, you might be tempted to tidy it up straight away, but it's a classic autumn hydrangea mistake - those faded flower heads can actually provide crucial protection from winter frost, and you could accidentally snip off next year’s developing buds.’

‘Cutting back stems now can also encourage tender new growth when the plant should be preparing for winter, and it may not have enough time to harden off before the cold weather arrives. Instead, leave the old flower heads in place - you can always do a final tidy-up in late winter or early spring, depending on the type of hydrangea you have,’ adds Shelley.

2. Treat different types of hydrangea accordingly

‘One of the biggest mistakes people can make in autumn is pruning hydrangeas too enthusiastically,’ says Pim Dickson, Senior Horticulturist at Fothergills. ‘The right approach depends on the type of hydrangea you have, because different varieties flower on different growth.’

‘Traditional mophead and lacecap hydrangeas, particularly hydrangea macrophylla, develop next year’s flower buds on stems produced in the previous growing season. Cutting these stems back in October can remove those buds and leave you with fewer flowers next summer. It is generally best to leave the main stems intact and retain the faded flowerheads over winter, removing them in spring once the risk of severe frost has passed,’ advises Pim.

‘When it comes to how to prune hydrangeas, such as panicle varieties like hydrangea paniculata, then these are different because they flower on new growth. These can be pruned in spring, when you can shape the plant and encourage strong new shoots. In October, resist the temptation to cut them back hard.’

‘As a general rule, remove dead, diseased or damaged stems when necessary with secateurs, but save substantial pruning for the appropriate time of year,’ adds Pim.

3. Assess plants and plan next year’s pruning

‘October is also a good time to assess established plants and, if necessary, plan how you will prune them next year,’ advises Charlotte McGrattan, Hardy Nursery Stock Buyer at Hillier Nurseries. ‘Pruning can influence both the size of the plant and its flowers: hard pruning produces vigorous growth with fewer, larger flowerheads; moderate pruning gives intermediate growth and flower size; while light pruning, removing only the previous year’s flowerheads, encourages earlier flowering with more numerous, smaller blooms.’

‘For now, the best approach is generally to leave the plant’s faded flowerheads in place and leave cutting back until spring, which will allow the hydrangea to provide some winter interest while protecting its new growth from the colder weather,’ adds Charlotte.

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4. Ease-off on watering and feeding

‘As the autumn weather cools, hydrangeas naturally start to slow down, so there’s no need to treat them as though they’re still in their peak growing season,’ advises Shelley.

‘Keep an eye on the soil rather than sticking to a set watering routine. If there’s a particularly dry spell in October, give your hydrangeas a good drink, but avoid the watering mistake of leaving them sitting in soggy soil. The same goes for feeding. There’s little benefit in encouraging fresh growth just before winter, so hold off on regular fertilising and pick this back up in spring when the plant starts putting on new growth again.’

5. Give the soil a layer of mulch

‘One of the simplest things you can do for hydrangeas at this time of year is to give the soil around its roots some extra protection,’ suggests Shelley. ‘A good layer of organic mulch, such as bark, compost, or leaf mould, can help the plant cope with changing temperatures.’

‘Mulching is a quick and easy job that can make such a difference during winter months, helping the soil hold onto moisture and keeping the roots more insulated as the ground starts to freeze. Make sure to spread the mulch around the base of the plant, but avoid piling it directly against the stems. Leaving a small gap around the base helps prevent the area from becoming excessively damp,’ adds Shelley.

‘Mulching is one of the most useful jobs you can do for hydrangeas in October,’ agrees Pim. ‘Applying a layer of organic matter, such as well-rotted garden compost, around the base helps the soil retain moisture, improves soil structure over time and provides some insulation for the roots as temperatures drop.’

‘Before mulching, remove any persistent weeds and water the soil if it is particularly dry. Spread a layer around the root area, ideally a few centimetres deep, but leave a small gap around the main stems rather than piling material against the crown. This helps reduce the risk of excess moisture encouraging rot.’

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6. Give potted hydrangeas some winter protection

‘Hydrangeas planted in the ground are generally well protected by the surrounding soil, but hydrangeas growing in pots or containers are much more exposed to cold temperatures, particularly around their roots,’ says Shelley.

‘Think about where your pots or containers are sitting as we head into winter. Moving them to a sheltered spot close to the house can help protect hydrangeas from cold winds and the worst of the weather, while still giving them enough light. It’s also worth checking that the pot has good drainage, as cold, waterlogged compost can cause just as many problems as dry soil.’

‘Container-grown hydrangeas need a little more attention because their roots are more exposed to cold than those growing in the ground,’ says Pim. ‘Move pots to a sheltered spot, such as close to a house wall, and consider insulating the container itself, but ensuring excess water can drain away.’

‘Resist the urge to repot hydrangeas simply because autumn has arrived,’ says Pim. ‘If the plant is healthy, it is generally better to minimise root disturbance and concentrate on keeping it protected until conditions improve in spring.’

‘And with increased rainfall in October, it’s easy to forget watering hydrangeas in containers, but be sure to check them regularly and prevent them drying out at this crucial time of year,’ adds Pim.

So don't prune your hydrangeas in autumn, but give them plenty of TLC and you'll help set them up for healthy growth next spring.