Hydrangea season is upon us, which brings to mind one of the most common questions gardeners ask. When do I prune? I still laugh to recall the many phone calls I had from readers after doing a story about hydrangea. Every one started like this: "My hydrangea didn't bloom this summer and I don't know why."
"Hmmm. Have you pruned it recently?" I'd ask. "Oh, yes," the caller would say. "We cut it way back a few weeks ago" or last fall, effectively killing the new growth that was already under way.
This is tricky business, for sure, so I go for the least complicated route: Whenever possible, do nothing. Most experts recommend leaving hydrangeas alone if you can, expecially the jumbo-jet native oak leaf, which shouldn't really be planted in a space it can easily outgrow. And anyway, I think hydrangeas look best when they're flopping and arcing all over the place.
But if you must prune, here are some very conservative suggestions. You can remove dead wood or do slight - SLIGHT - pruning at any time for shaping. If you have to prune for size, some folks take out a few branches, no more than about one-third, in winter or very early spring to rejuvenate the plant. But don't do more or you'll be in trouble.
Once the blooms are done, you can leave them on 'cause they're fun to look at through fall and winter OR you can deadhead (remove) them as you would the spent blooms of other perennials. No one's out in the woods deadheading hydrangeas, so clearly these dead flowers don't need to come off. I'd just as soon leave them till spring, then in one of those happy springtime rituals, make way for new.
Hydrangea macrophylla, the so-called "mophead" shown here, was planted in my garden six years ago from a single bloom in a pot for Mother's Day. You should see it now - it's a giant, and more beautiful than ever this year. Maybe that's due to the great spring we had. Or because it was expertly thinned last winter. (Not by me, of course.)
In any event, unless it's my imagination, it's emerged this season straighter, with stronger - and somehow darker - stems, than I remember. I've even cut them to bring in the house and they've survived for several days.
So while the best strategy is to leave your hydrangea alone, you can prune out the dead branches or a little of the old growth on occasion. I wouldn't make an annual habit out of it and I'd restrain with a floral-patterned straight jacket any significant other who exhibits a compulsion to prune this fall. Even better, hide your pruners.
