Help With Hydrangeas, Those Flowery Harbingers of Fall

I have been at the center of my fair share of household garden scandals. But of the many garden crimes I’ve committed, no scandal to date has been as controversial as the year the hydrangeas didn’t bloom. Nobody asked questions; they didn’t need to. It wasn’t a mystery. We all knew exactly what happened and who was to blame.

It was a brisk, sunny morning in late March, maybe early April, as I stood in front of the still-dormant hydrangeas. My gut was telling me “Early spring is pretty late to be pruning this kind of hydrangea.” But after having neglected them until that point, my big brain chimed in and proclaimed,

“You’ve pruned other hydrangeas back this late in the season and they’ve been fine, so...” A solid argument. As the shears snipped into the first few branches I became increasingly committed to seeing the project through.

Famous English gardener Christopher Lloyd makes a statement in his book “The Well-Tempered Garden” that uses a guiding principle:

“If you postpone a job until the ideal moment from a plant’s viewpoint, the chances are you will miss doing it when that moment arrives, for reasons of forgetfulness and preoccupation with other matters. And so, to the amateur gardener’s eternally repeated question, ‘When should I?’ and ‘What’s the best time to?’ I’ve concluded that nine times out of 10 the answer is ‘When you’re thinking about it; when you’re in the mood.’ ”

This is a great piece of advice when I want to convince myself it’s totally cool to transplant something during the middle of a summer drought. Or that working in nasty weather sucks more than being a couple weeks past due for a perennial to get divided. But for certain plants, like hydrangeas, there is absolutely a best time to tend to them, and I’ve suffered the consequences of not managing to coordinate my thoughts and moods around when their particular seasonal needs should be met.

Hydrangeas are unique in the scope of my garden to-dos as my moods toward them have typically been dictated by how confused I get when I start to think about them. For me, they fall into a category of plants I like to call “What kind are you, again?” Clematis and raspberries are also included in this group. These plants are of the flowering or fruiting sort that requires you to know the difference between “new” and “old” wood because some varieties produce exclusively on new wood while others wouldn’t dream of adorning anything but older, more mature, distinguished wood.

Being able to confidently make these distinctions is important to determining when and how they are pruned. However, trying to remember the stats year after year is a great source of frustration, which typically results in my pruning procrastination, as evidenced by the no-bloom scandal of 2023.

You may be thinking, “Why wouldn’t you just look it up real quick?” And I do, but by the time I’m asking, it’s when the shrubs are dormant and if there are multiple varieties in a landscape remembering what kind each one is becomes all the more difficult and so they get treated equally. So that’s why this year I’m doing the long overdue research to commit the facts to memory once and for all.

Where I went wrong with the hydrangeas in my garden wasn’t even that I had pushed pruning into spring, but rather that I thought late winter would have been the right time to do it. In actuality, my hydrangeas are supposed to be pruned right now in early fall as the blooms are fading.

The varieties I have are “big leaf ” (also called mophead or florist’s hydrangeas) and “lacecap,” which are in the Hydrangea macrophylla family. Varieties in this family primarily bloom on old wood (some newer cultivars will bloom on new and old, but for the sake of simplicity, regard them as old wood bloomers), which means the buds for the next season will be set by late fall. Oakleaf hydrangeas also require early fall pruning.

Hydrangeas that bloom on new wood are panicle varieties (Hydrangea paniculata; flower heads shaped like cones) and smooth varieties (Hydrangea arborescens; primarily bloom white and are native to North America). These can be pruned in either spring or fall, though spring is better to avoid potential damage to new growth.

Curious, I pulled down my copy of “The Well-Tempered Garden” to see what Lloyd had to say about pruning hydrangeas.

“Never prune your hydrangeas by shortening their shoots.” Oh dear. He goes on, “The only pruning should be by thinning out.... Over a period of many years, the average hydrangea needs to renew itself. By cutting away its oldest and least vigorous branches you admit light and space to the center of the bush and encourage the development of a few (not too many) new branches.”

Ah! So, I wasn’t completely inaccurate in waiting until March to tend to the hydrangeas. My only mistake was cutting from the entirely wrong end. I think we can laugh about it now.

Overall, regardless of what kind of hydrangea you have, go with whichever pruning method works best for your garden, and whatever mood you happen to be in when it crosses your mind. Though I hope the mood strikes now because now would be a good time.