Hydrangeas: Pruning them in March - not yet!

The days are getting longer, the daffodils are flowering, all sorts of plants are budding, leafing, and generally there is a feeling in the air that it might be time for me to get back in shorts, oh happy day!

You might even see that your Hydrangeas are budding nicely: - left -  and you might be thinking that it's time to give them their spring prune.

But fie! Not yet! It's too early!

I used to work for a lovely lady with vast amounts of Hydrangeas in her garden, and she was terribly strict about never allowing me to prune any of them before May.

Yes, May. 

"Not until all chance of a late frost is gone," she would admonish me. Every year.

Alas, she's gone to that great Compost Heap in the sky now, but I still think of her in spring, when I am faced with ratty-looking Hydrangeas, and Clients who want me to cut them down.

As a compromise, I do allow myself to trim off the dead flowers from last year, because although the accepted wisdom is that they provide a sheltering micro-climate, keeping the frosts away from the new buds: well, I find that by the end of winter I'm sick and tired of looking at them, so off they come.

But I don't shorten the shoots to "the first pair of fat buds" as is so often recommended. Not yet, anyway.

Instead, I might shorten a few of the shoots, if they are ridiculously longer than the majority. And I'll go through and nip out any distinctly dead shoots, which are generally easy to spot because they are a pale, light grey and - more to the point - they have failed to produce any signs of buds, when all around are doing so.

This intermediate prune tidies up the plant, and removing dead wood is always a good thing: but it leaves a lot of growth in place, just in case we have that fabled late frost.

What happens, you might be wondering, if you ignore this advice, and prune your Hydrangeas now, in mid March?

Well, if you are lucky, nothing: but if you are unlucky and we have a late frost...

...as we did last year, in 2021, this photo being taken on the 12th of April.....

... then you are likely to end with something like this, taken the following week...

As you can see, it looks as though someone has run a flame thrower over the plant.

Lots of crinkly, wilted, ruined, foliage.

Of course, the plant survives: because I had only nipped off the dead brown flowers, and had resisted the urge to prune down to those nice fat buds, there were plenty of nice, fat buds (okay, by mid-April they were "good strong leaves" rather than "nice fat buds" but you get the idea) at lower levels, which were undamaged by the frost.

And, of course, I resisted the urge to trim off all the damaged material, as this was only the middle of April, and there may have been more frosts to come. So we had to put up with it looking like this for just another couple of weeks, until we were safely into May, and until the Hawthorn blossoms were out.

There is a lot of sense in that old saying, "cast ne'er a clout, till the May be out."  "May" in this case being, as you probably know, not the month of May, but the plant Hawthorn.

Sorry, what was that? You didn't know? Well, the Hawthorn, that familiar hedging tree/bush/shrub, is known colloquially as "May".  And it flowers quite late in spring, well after the Blackthorn (the one which produces Sloes, later in the year) which is pretty much the first hedgerow tree to flower in spring.

So the idea is that you don't "cast a clout", ie remove a layer of winter clothing, until the Hawthorn is "out", ie in flower.

The clever part is that Hawthorn flowering time is related to temperature, not to day length: so it doesn't flower on the same day each year, it flowers only when things have warmed up a bit. 

All of which means that it is not a good idea to prune your Hydrangeas just yet: removing the dead flowers for cosmetic improvement is ok, but don't cut the stems down at all, until we are nearing May!

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