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Shrubby Hydrangeas - to prune, or not to prune?

  • Shrubby Hydrangeas - to prune, or not to prune?
  • Shrubby Hydrangeas - to prune, or not to prune?

We're at that awkward time of year – the shrubby hydrangeas are looking really tatty, and at the same time are bursting into life, but it's too early to prune them properly, as we are certain to have a few more frosts before the month is out.

So what is the best thing to do?

My answer is to do a partial prune, right now: this is a technique I have developed over the years, which satisfies Clients who are sick and tired of looking at dead brown flowers, but which does not place the plant at risk.

The risk, in case you didn't know, is that if you prune a Hydrangea “properly” and then we get a hard frost, the frost can damage the new buds. You then have to remove those frost-damaged buds, and this can leave you with a mis-shapen, or drastically smaller-than-required plant.

My partial prune consists of removing the horrible tatty brown flower heads from last year, but rather than cutting the plant back to the traditional “pair of nice fat buds”, I merely take off a few inches of stalk: often I will simply take off roughly the same amount all the way round, leaving a neat shape.

If there is time, I lean inside the plant and remove any stems which are obviously quite dead: such stems are usually pale grey-white, and don't have any sign of buds whatsoever, and as soon as you cut them, you can tell that they are dead. If you are not quite sure whether a stem is dead or not, take off just an inch or two and look at the cut end: if it is hard, brown and dry, the stem is dead, but if it is soft and white or green in the middle, then it is still alive and there is hope for it yet.

I usually also take the opportunity to remove any weak and spindly stems, any misplaced ones, any that are growing too low to the ground, and any that are shooting off in the wrong direction, and spoiling the outline of the plant.

Opening up the centre of the plant in this way allows air, light and rainwater in, which has the dual benefit of encouraging new growth, while discouraging bugs and diseases – what I call a win-win! - and also making it easier for me to do the proper prune in a few weeks' time, when all risk of frost is past.

If, however, you are a bit nervous about damaging your Hydrangeas, then just take off the dead flowers, and do the thinning when you do the main post-frost prune: I tend to do it now because I think it prevents the plant wasting energy on stems that are going to be removed in a few weeks' time anyway, not to mention the fact that it looks neater, but it won't do the plant any harm if you don't do it now.

I've attached two photos of a large Hydrangea halfway through the process, one photo from each side: as you can see, the overall size of the shrub is reduced by only few inches, leaving plenty of room for a proper prune later on, but it improves the appearance quite dramatically!

Comments (4)

  1. Grower

    Helene U Taylor

    Hi Rachel
    Great info and useful stuff :-)
    Here is a photo of one of the 3 hydrangeas I had in my previous garden where I lived for 14 years, it grew so tall that I had to cut it down by half every 3-4 years to keep it slightly below the 2m tall fence behind it. I took cuttings from two of the hydrangeas I had before moving and I now got 4 little plants here in my new garden.

    I had to smile when I read your post, I sometimes wonder if we live on a slightly different planet here in London – or at least a different country. My hydrangeas were all pruned to ‘second pair of fattest buds’ – in early February, after all the roses and clematis’ were finished pruned. I never had any frost damage :-)

    • Shrubby Hydrangeas - to prune, or not to prune?
  2. Grower

    Rachel the Gardener

    Wow, Helene, that's gorgeous!

    And yes, London has a very select micro-climate! Out here in South Oxfordshire it's definitely "not before late April" for many of these jobs, and some of my gardening colleagues further north have to wait much longer!

  3. Grower

    Alan Wardle

    I would cut the Hydrangea in the photo to at least half the height or even lower. Here in Hampshire we pruned our Hydrangeas about 3 weeks ago. If they get plenty of water then you could cut them down to a foot high. Then remove the dead wood from the base. Either prune above a bud or what appears to be a bud location. If you cant see a bud then just cut to the height you want it wont damage the plant.

  4. Grower

    Helene U Taylor

    Hi Alan, as I say in my comment I used to cut my hydrangea by half every 3-4 years to keep it below the 2m fence. It grew very quickly up again! It didn’t flower so prolifically the year I pruned it hard so I didn’t want to prune it down every year. It worked well for me doing it with a few years between each hard prune and the hydrangea was a spectacular sight every summer.
    I moved house in May 2015 so I no longer have this hydrangea – the new tenant living at the house is hopefully enjoying it. I took a couple of cuttings last spring which are nice, healthy plants now with lots of flower buds.

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