Knowing when to prune hydrangeas is the key to encouraging new blooms. But knowing when in spring can feel tricky because the weather is still somewhat unpredictable which can adversely affect the optimum timing.
How to prune hydrangeas and when to prune in the UK depends on the type of hydrangea you have, as different species require different approaches. Some require cutting back this spring before it's too late, with some experts recommending pruning from February if there's no need to avoid it to protect plants from frosts.
But generally, the consensus is spring. So how late in spring is too late to cut hydrangeas back? What is the cut-off point for pruning in March?
When is it too late to cut back hydrangeas?
“It’s always best to prune back hydrangeas in early spring before the new growth begins in earnest, so you’ll want to tackle this job just as leaves are beginning to show," says Andrew O'Donoghue, one of the co-directors at Gardens Revived. "Any later and you risk cutting off next year's flower buds."
"The only exception to this rule is climbing hydrangeas, as these are ideally pruned after flowering in summer.”
Experts recommend pruning hydrangeas when the weather is dry and mild, which can cause the process to be delayed even in spring.
Similar to when first cutting the grass after winter you should aim until temperatures are consistently above 8 degrees. Keep an eye on the rain forecast also, as pruning during Wet conditions can promote the spread of diseases, so is always best to avoid it.
Andrew then points out that the other optimum time to prune hydrangeas if you miss spring is once the flowering season ends in late winter.
When to prune different types of hydrangea
There are three types of hydrangeas, all of which require a different approach to when and how you prune each, as our expert professional garden designer Marlene Lento explains below...
Hydrangeas that bloom on new wood
"These hydrangeas produce flowers on new growth that emerges in the current season," explains Marlene. "They can be pruned in early spring before new growth begins. Examples include Hydrangea paniculata, and Hydrangea arborescens."
This variety can also be pruned in winter once the flowering season has finished. To prune this type you need to take the following steps:
- Cut back the stems to a few inches above the ground.
- Remove any dead or weak stems.
Hydrangeas with minimal pruning requirements
Some hydrangeas require very little by way of pruning, including climbing hydrangeas as Andrew mentioned before.
"Certain types such as Hydrangea anomala subsp. petiolaris (Climbing Hydrangea), require minimal pruning, " Marlene agrees. "You can remove any dead or damaged growth in early spring or late winter."
So this isn't a hydrangea variety that you have to worry about being too late to cut back this spring, because it might not require any pruning at all.
Hydrangeas that bloom on old wood
These types of hydrangeas produce flower buds on stems grown the previous year.
"These should be pruned immediately after flowering, which is usually in late summer or early autumn," says Marlene. "Examples include Hydrangea macrophylla, Hydrangea serrata, and Hydrangea quercifolia."
- Prune out any dead or weak stems.
- Trim back the flowering stems to a pair of healthy buds.
FAQ
What is the best time of day to cut hydrangeas?
So we now know when in terms of calendar months but what is the best time of day to cut hydrangeas? Because similar to knowing the best time of day to water your lawn that too can hugely affect the results.
"The best time of day to prune hydrangeas is in the morning, ideally after the dew has dried but before the heat of the day sets in," advises Marlene. "Pruning in the morning allows the plants to recover during the day, minimising stress and reducing the risk of disease."
"As for weather conditions, it's generally recommended to prune hydrangeas when the weather is dry and mild. Avoid pruning during periods of extreme heat, cold, or wet conditions. Wet conditions can promote the spread of diseases, and extreme temperatures can stress the plants."
What happens if you leave it too late to prune in spring?
Pruning is highly recommended but not necessarily essential. As our resident garden expert, Holly Crossley explains: "Most hydrangea varieties can be cut back in early spring, as leaving the old flowerheads on over winter protects the stems from frost, as well as providing sculptural interest to the garden. However, if you forget (or leave it too late), don't worry – they should still flower, but the plants may not look their best."
