This summer has been scorching, and we aren’t the only ones who’ve been feeling it – I’ve seen a lot of hydrangeas turning brown this month, and that can mean one of a few things.
Before you jump ahead and learn how to deadhead hydrangeas, it’s worth thinking about the underlying causes of brown leaves and flowerheads – especially in light of this summer’s high temperatures. I, for one, am keen to know why I’ve spotted so many brown hydrangeas over the past few weeks.
Of course, there are a myriad of reasons why a hydrangea might be turning brown – but this time, we’re focusing on why your plant is suffering as a result of the recent heatwaves, specifically (and how to rescue them!).
What’s causing hydrangeas to turn brown this summer?
Troubleshooting starts with identifying the cause, so let’s start by taking a closer look at what’s causing your hydrangea plants to turn brown this summer.
1. The heat
If you’ve been struggling to keep your garden cool in recent heatwaves, your hydrangeas have likely been feeling the heat, too.
Too much sun, combined with high temperatures, can effectively sunburn your hydrangeas – especially if you’ve planted them in a spot that gets full sun.
‘A poor planting location can result in hydrangeas turning brown and suffering from heat stress,’ says Richard Barker, commercial director at LBS Horticulture. ‘If you think that sunlight exposure is the problem, you may need to relocate the hydrangea or provide it with shade during the hottest parts of the day.’
Some shade netting, like this shade cloth from Amazon, can help shield your plants from the blazing sun, especially if temperatures rise again over the coming weeks. Just make sure you pull it taut and fasten it securely to whichever frame you’re using to safeguard wildlife.
2. Underwatering
What goes hand-in-hand with heat stress? Underwatering – and it goes without saying that if you haven’t been hydrating them enough this summer, your hydrangeas are far more prone to turning brown.
‘During the warmer weather, underwatering can make hydrangeas turn brown and crispy,’ explains Richard. ‘In milder cases, only the tips of the petals will turn brown, but it’s possible for the entire flowerhead to turn brown.’
If you’re growing hydrangeas in pots, it’s worth thinking about bottom watering to help them make the most of every drop.
3. Overwatering
Of course, you could be overwatering your plants, too. Waterlogging is another cause of hydrangeas turning brown, so if you’ve been overcompensating to keep your plants hydrated during 2025’s heatwaves, you might be doing your plant more harm than good. It’s possible to overwater your plants in the summer, after all.
‘It’s actually easy to overwater a hydrangea, especially in the summer,’ says Richard. ‘If the hydrangea flowerheads are turning brown and yellow, this suggests that they are being overwatered, and the heads may begin to fall off the plant.’
It’s difficult to save an overwatered plant if it’s too far gone, so if you suspect you’ve overdone it, nip any damage in the bud by giving your plants a break from watering.
How to revive a brown hydrangea after the hot weather
So, how do you revive your hydrangea plant after a scorching 2025 summer?
It depends on what’s causing it. If you’ve overwatered your shrub, you’ll need to scale the watering schedule right back – but the most common culprits this year are high temperatures and underwatering.
‘If your hydrangea has turned brown due to the recent hot weather, you should water it deeply, ensuring that the soil is thoroughly moist,’ says Richard. ‘If the plant is in an area where it receives a lot of sunlight, consider moving it somewhere with dappled shade or provide it with temporary shade.’
You’ll also need to trim away any brown parts of the plant.
‘Remove any completely brown, dried-out flowers and leaves, as these will not recover and their removal will prevent diseases,’ Richard explains.
So, you can revive your brown hydrangea plant, even after the intense heatwaves we’ve experienced this summer.
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