Question of the Week © 2017 Mike McGrath
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Relaxing the Rules for Holiday Holly Pruning
Q. My holly has grown so well that it's covering our windows. I would like to give the bushes a really good pruning. What is the right time of year to do this?
---Leah in Boalsburg, "three miles from State College in the middle of Pennsylvania"
A.Well, you know probably all know that I always warn against pruning in the fall.
Fall pruning is especially bad for Spring bloomers like azaleas, rhododendrons and lilacs because those plants make the following year's flowers in the summer. But fall is when people always seem to have too much time on their hands AND when they suddenly notice that their decades-long neglected plants have—shockingly—grown "too big". Unfortunately, a lot of this misguided attention is directed at azaleas, which I can save if the pruner emails to ask "can I…"; but more often than not, the email reads, "I just whacked mine back really hard and…"
Hey, McGrath: The question is about hollies. What about hollies?
But the biggest reason not to prune in the fall is that perennial plants are entering dormancy—and pruning before they get there stimulates growth that's very susceptible to winter injury, and saps vigor that the plant might need to survive winter.
WHAT ABOUT HOLLIES?!
Lovely and useful plants. The basic term 'holly' encompasses a large number of different species: English, Chinese, Japanese and quite a few native Americans—including the winterberry, a shrub that drops its leaves in the fall, and the classic "American holly", an evergreen tree that can reach 30 feet in height.
…Although most people only think of the classic English holly, whose glossy green leaves and bright red berries have become synonymous with Christmas—even though use of the plant's cut branches as festive decorations predates Christianity. (So there's no religious preference here; you'll also find holly in stylish Druid households over the winter!)
Now, time for me to stop beating around the shrub and answer the question.
Paul Meyer, Director of the Morris Arboretum of the University of Pennsylvania, which has an impressive collection of almost two hundred different kinds of hollies, tells me that virtually all types tend to be very pruneable, meaning that they should grow back nicely after pruning—including what's called 'drastic pruning'.
It's important to note here that, while most hollies should survive a 'hard pruning' (provided it's done at the right time of year), the result will not be sudden and dramatic rejuvenation. Instead, the plant won't be very pretty for a season or two. Paul notes that the only hollies they cut back hard at the Arboretum are out of public view. For specimens that are more visible, the staff takes several seasons to reduce their size, cutting back no more than a third of the plant every winter for several years —a tactic that should always be a homeowner's first choice: Slow and steady wins the race. (And duct tape is not meant for plant repairs.)
The ideal time to prune hollies is in the dead of winter—especially for drastic pruning. Normal cutting and shaping can be done in either winter or Spring—or even early summer if you want to see where the berries form and remove branches that are less showy. The worst time is late summer through early fall.
Luckily, we're just now leaving 'early Fall' and entering a fairly safe time for people who want to use cuttings from their own plants to make wreaths, swags and stuff, depending, of course, on your climate and how cold it's been. You certainly don't want to prune until you've had a couple of hard frosts. And then I'd wait until the middle of a cold spell—ideally after two or three cold days and freezing nights with two or three more of the same predicted. And then do your pruning at the very end of the day.
I'm thinking like a plant here. If it's cold but sunny and I'm just a tiny bit shy of going fully dormant for the season, I might still get a little sappy midday. But at the end of the day, when it's going to be cold and dark afterwards, there won't be as much stimulation.
Now I have to admit that none of this is in The Spaulding Guide…
…which I also have to admit is about baseball and not gardening. (But they're the same thing.)
Anyway, the principles are very sound, and I've done this myself every holiday season. Just wait until the conditions are right. The same goes for conifers; as long as you're pruning properly for that specific plant, you can safely harvest some evergreen branches the same way. Just don't destroy the look of the plant.
Oh—and two important things to remember.
One: The old legends say that if men bring holly into the house, they will 'rule the roost' in the coming year.
And the second thing: Whatever your sex, don't bring holly berries into the house if you have children or pets who might ingest them. Although birds love the fruits, they're toxic to people and pets.
(But don't worry men; even if you can't bring holly inside, you can still sing ancient Saturnalia chants that claim you're in charge: http://en.wikipedia.org/wiki/The_Holly_and_the_Ivy).