Everything you need to know about growing hydrangeas
Growing hydrangeas is a no-brainer if you want a garden with year-round interest.
They flower from mid-summer until the end of the year.
And in autumn, some hydrangeas have brilliant red and gold leaf colour.
Then the sculptural shapes of their flowers, dried to papery elegance, make wonderful outlines in the frost over winter.
They do have, perhaps, something of a suburban reputation. As do many shrubs.
But at the Landscape exhibition last week, there was a definite sense that shrubs are ‘coming back.’ And growing hydrangeas is part of that.
I visited Signature Hydrangeas, specialist growers of hydrangeas to talk to hydrangea expert, Roger Butler, about the basics of choosing and growing hydrangeas.
The different hydrangea types – start with macrophylla…
Hydrangeas make much more sense once you know the most common types. And that’s important because there are basically two very different kinds of pruning, depending on what type of hydrangea you have.
But even if you haven’t kept the label, it’s relatively easy to tell which type of hydrangea is which by looking at either the flower shape or the leaf shape.
The best known are the macrophyllas, which divide into mop heads and lace caps.
The fashionable Hydrangeas arborescens and paniculata…
The ‘arborescens’ hydrangeas are known as ‘wild hydrangeas’ or ‘smooth hydrangeas’ in the US.
Even if you have never considered growing hydrangeas, you will probably have admired the white puffs of Hydrangea arborescens ‘Annabelle’ in smart gardens over the last ten years.
Hydrangea paniculata has cone-shaped flowers. The fastest-growing hydrangea in popularity is now the paniculata type, according to Roger Butler. ‘We’ve consistently sold more paniculatas over the last few years than any other hydrangea.’
Top garden designer Philippa O’Brien agrees, telling an audience of garden designers at this year’s Landscape show that Hydrangea paniculatas are on trend.
And oak leafed hydrangeas…
Hydrangea quercifolia literally means oak-leafed hydrangea. No further explanation needed.
Oak leafed hydrangeas are stylish, and they’re also even more easy-going than most hydrangeas. They’ll put up with dry or cold conditions better than the other hydrangeas.
Growing hydrangeas for their colour
People are more confused about hydrangea colours than anything, according to Roger. ‘The macrophyllas change colour according to the pH of the soil. Hydrangeas on very acid soil will be blue, but the same hydrangea will be pink if it’s grown on alkaline soil. So people buy a blue hydrangea, plant it in their garden and then it comes up pink.’
If you don’t have acid soil, but want blue hydrangeas you can keep it in a pot and treat the soil with a specialist hydrangea feed, such as Westland Hydrangea Plant Feed. Note: links to Amazon are affiliate, see disclosure.
How do you choose hydrangeas?
If you’re thinking of growing hydrangeas, Roger Butler advises you to start by thinking about your site and soil. ‘If you’re planting hydrangeas in a sunny spot, you should choose paniculatas or arborescens varieties.’
‘And if you’ve got light to heavy shade or woodland conditions, the macrophyllas are the best bet. The flowers of macrophyllas will burn in full sun, so they do need some shade.’
When you should plant hydrangeas?
‘You can plant hydrangeas at virtually any time of year,’ says Roger. ‘But if you plant them in the summer, keep them well watered in dry weather.’
Which plants grow well with hydrangeas?
Roger thinks that hydrangeas work best on their own. ‘They make a dramatic statement in blocks or rows. And macrophyllas are quite dense plants so you wouldn’t want to plant something that needed a lot of sun beside it.’
Can you move hydrangeas?
If you think you’ve planted your hydrangea in the wrong place, you can move it, says Roger. ‘The best time to move hydrangeas is the end of October or early November. Get it back into the ground as soon as you can.’
Growing hydrangeas in pots?
Hydrangeas grow very well in pots, says Roger. ‘There’s an increasing number of hydrangeas now sold as patio or indoor plants.’
If you buy or are given a hydrangea in a pot, with lots of beautiful blooms, it may have been treated to dwarf its growth and maximise its blooms. So this can mean that if you then plant it out in the garden, it will grow very differently next year.
So if you’re growing hydrangeas for the garden, it’s probably best to buy them from a hydrangea specialist or nursery that grows them for planting in the garden. You can also then discuss what your growing conditions are with someone who will know which hydrangeas will be best for your site.
And you can be reasonably sure that the hydrangea you buy will continue to grow like that and look like that over the next few years.
How to prune hydrangeas
If you’re growing hydrangeas, you need to know which type you’ve got in order to prune them.
The macrophyllas (the mop heads and the lacecaps) and the oak-leafed hydrangeas need light pruning. Roger advises you to snip off the dead flower heads in March, taking off the top pair of leaves. You should cut down to the first fat bud you see. That’s next summer’s flower.
There are other hydrangea varieties, such as Hydrangea serrata and Hydrangea aspera, which are pruned lightly as for Hydrangea macrophylla.
If you cut macrophyllas and oak leafed hydrangeas down too far, you’ll lose the flowers. However, you may cut out whole stems if you want to thin the plant or improve its shape.
However, the paniculatas and the arborescens need hard pruning. Roger says you should snip them back to two buds above the ground in February or early March.
What about hydrangeas and pests?
Deer and rabbits don’t like hydrangeas because the leaves are mildly toxic, according to Roger.
He says there are some problems with slug and snail damage. But at Signature Hydrangeas, they manage these with natural solutions (such as nematodes) and by gardening in a wildlife-friendly way so that the birds, frogs and hedgehogs help keep slugs and snails under control.
Personally, I’ve never found any slug or snail damage on my hydrangeas, but I do have a lot of birds in the garden. And I grow dahlias, which presumably are tastier to the slugs.
Do you need to fertilise hydrangeas?
I don’t think I’ve ever fed my hydrangeas. That’s one for the to-do list.
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Why isn’t my hydrangea flowering?
The main cause of hydrangeas not flowering is that they’ve been pruned wrong, says Roger. The flower buds on macrophyllas are at the tops of the stems, so if you prune them back too far, you will lose the flowers.
Why is my hydrangea wilting?
Hydrangeas in pots often wilt, either because they’re short of water. Or they may be sitting in water, says Roger. ‘So if your hydrangea is dry, give it a good soaking, but if it’s sitting in water, make sure it drains off,’ he says.
More about growing hydrangeas in this video:
You can see more hydrangeas here:
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