With their huge pompoms and long flowering seasons, they are some of the best showpieces of the British garden – but if you’re wondering how to revive tree hydrangeas like a pro, you’re not alone.
Hydrangeas are one of the easiest and most popular ways to lighten garden borders from early summer to fall. But after a few years, many gardeners notice the same frustrating problem: their once lush hydrangea has become woody, leggy and stubbornly unwilling to bloom (boo, hiss!).
This is a common problem, especially with older hydrangeas that have not been pruned for a while. Over time, hydrangeas can develop thick, woody stems that produce fewer fresh shoots, which in turn means fewer of those spectacularly showy flowers, even if you’ve chosen the right time to kill them. The good news, however, is that a tired-looking hydrangea can rarely be saved.
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How to revive tree hydrangeas
With the right pruning technique and a little patience, you can fully revive tree hydrangeas. In fact, many gardeners are surprised by how dramatically hydrangeas can recover once they are given a chance to produce new growth.
Even before you i think however, to abbreviate anything, it’s important to know what a type of hydrangea you’re dealing with. Different varieties flower on different types of wood, and pruning at the wrong time can accidentally remove the very buds that would have produced flowers that year.
As Maurice Hankinson, Director of Hopes Grove Nurseriesexplains, understanding your hydrangea variety is the key to bringing an old plant back to life.
Maurice Hankinson is the founder and managing director of Hopes Grove Nurseries Ltd, the UK’s only specialist hedge plant grower and retailer. He set up the thriving business in 1992, shortly after graduating with a commercial degree in horticulture from Writtle College, Essex.
“There are several common types of tree hydrangeas that gardeners grow,” he says.
“Hydrangea macrophylla – often known as mophead or lacecap hydrangea – blooms on old wood, while Hydrangea paniculata and Hydrangea arborescens bloom on new wood.”
This distinction matters because pruning the wrong stems at the wrong time can remove buds that would have produced flowers that year.
Hydrangea macrophylla forms its flower buds the year before, which means aggressive spring pruning can eliminate flowering. Paniculata and Arborescens varieties, however, produce flowers on new growth, making them much more forgiving when it comes to pruning.
(Image credit: Getty Images / John Caley)
Once you’ve determined what you’re working with, you can move on to the following steps…
1. Check for winter damage first
Before doing any major pruning, it’s worth checking to see if winter has damaged parts of the plant.
“Wait until late spring when new growth appears,” advises Hankinson. “Try the scratch test: gently scrape the bark with your fingernail. If it’s green underneath, the stem is alive. If it’s brown and dry, that part is dead.
He also recommends looking closely for other signs of life. “Check the plant for hollow stems, split wood and signs of buds,” he says. “If there are no swollen buds, this could potentially be a sign that the hydrangea did not survive the winter.”
Removing the obviously dead stems first helps you see what healthy growth remains and prevents unnecessary pruning.
2. Prune
If you are growing hydrangea macrophylla, restraint is essential when trying to revive a woody plant.
“Remove only dead, damaged and diseased stems by cutting back to green wood using the scratch test,” says Hankinson. “You can also remove the tops if they were damaged over the winter.”
Because this variety blooms on old wood, heavy pruning may accidentally remove the buds that would have produced this year’s blooms.
“The key is patience,” he explains. “Even if the top growth has died, new shoots can still appear. The flowers will grow on old wood, so over-pruning will mean fewer or no flowers this year.”
(Image credit: Getty Images / piotrmilewski)
If your plant is a panicle hydrangea or a tree hydrangea, gardeners can be much more confident with their pruning.
“These varieties can tolerate a harder spring cut,” says Hankinson. “Stems can be cut back to about 25cm to 60cm from the base, and smooth hydrangeas can even be trimmed back to ground level.”
Because these hydrangeas bloom on new growth, cutting them back encourages fresh shoots that will produce blooms later in the same season.
“Always use sharp garden shears and make a clean cut just above the bud,” he adds.
3. Help your hydrangea recover after pruning
Once the pruning is done, a little follow-up care can help the plant recover and produce strong new growth.
“After pruning, feed lightly with a balanced, slow-release fertilizer, water liberally and mulch around the base,” Morris recommends. “Just make sure the mulch isn’t too close to the stems.”
It makes a lot of sense; after all mulching helps protect the roots, improves soil moisture and regulates the temperature around the plant. We are big fansbasically.
Frequently asked questions
How to bring hydrangeas back to life?
If you want to bring your hydrangea back to life (or, you know, you’re sick of it looking like a bunch of grey, brittle sticks come early spring), then Christopher O’Donoghue, director of Gardens revived urges patience.
“Before you play Dr. Frankenstein, scratch a stem to see if it’s green underneath,” he advises. “If it’s green, leave it in. If it’s brown and shriveled all the way through, that particular stem is dead.”
Whatever you do, Christopher says the trick is not to panic prune in March. “Many varieties (like Bigleaf) flower on ‘old wood,’ and those dead-looking canes are actually holding this year’s flowers,” he points out.
“If the leaves are yellow with green veins (chlorosis), the soil pH may be poor or need iron. A dose of acid fertilizer can often wake them up.”
How far can you prune tree hydrangeas?
If you want to prune tree hydrangeas without accidentally killing next year’s flowers, then you need to spend some time looking at the types of hydrangea, says Hen Christopher O’Donoghue, director of Gardens revived.
“Hydrangeas annoyingly defy this one-size-fits-all approach to gardening,” he says. “Some grow on new wood and can be cut down immediately; others grow on old wood and must be handled much more carefully.
With time, care, and the right pruning approach for your particular variety, even a very woody hydrangea can be brought back to life. And if you keep up with all of this, you’ll be rewarded with healthier growth and better blooms for many seasons to come.
