When it comes to the world of trees and shrubs, there exists, for those of us who care, a god. His name is Michael Dirr. A professor of horticulture at the University of Georgia, he has written a book, Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture and Propagation and Uses, (otherwise known as the bible) which is the most widely sold reference book in the world of horticulture and landscape architecture. It has sold over 250,000 copies, which is fairly impressive for a book with small black and white pen and ink drawing of leaves.
I mention these credentials, because I love being right, and Michael Dirr has confirmed that, once again, I am. I speak of course, about not pruning hydrangea.
Why, you might ask, are you bringing up hydrangea pruning now in the depths of this hideous weather? No one is really playing outside in the garden anymore, are they? Well of course they are I would reply with a snort if you asked me this question face to face, and I bring this up now, because right now is when Michael Dirr is chatting via email with a colleague at work. Imagine that. He’s emailing with god.
So hopefully you all remember everything I’ve taught you previously about not touching your hydrangeas until springtime. That you are allowed to deadhead (remove the dead flowers) but that you really should not do any pruning until spring time, and then, when it comes to the macrophyllas and serratas (the mopheads and the lacecaps) you do not do any pruning at all, you just remove dead wood. You actually don’t prune querifolia or petiolaris either (oakleaf or climbing hydrangeas) but most people just plant the former two varieties and that’s all they care about. So, since you’ve been paying attention over the last few years, you therefore have not whacked back your hydrangeas when you raked up your leaves. In fact, I’ve made you so paranoid you won’t even make eye contact with any shrub that starts with the letter H.
I’m here to tell you what Michael Dirr wants you to do with your pruners. Nothing. He too wants you to wait until spring. Even when it comes to your paniculatas, the panicle types – Tardivas, Limelights, Pee Gees, etc. I know people who like to prune these now, I’ve even been known to start to cut mine back in February, when I’m bored, but folks god has spoken and he’s saying wait, and recommending, “… a light removal of spent inflorescences.”
The reason I feel, is of course, simple. As this past year demonstrated, we don’t know whether stems are going to be alive or dead next spring, since none of us can predict the winter. For most of us this past spring, all those stems of our Endless Summers and Nikko Blues were toasted by the winter and new growth wasn’t coming in on old wood, it was only emerging from the base or the crown of the plant. That’s why most hydrangeas were not flowering; the only growth was new growth and most hydrangeas bloom on old growth. Endless Summer is a reblooming hydrangea, which means that it blooms on old wood as well as new wood. All reblooming hydrangeas are also unusual in that they have flower buds on 85% of the buds on old wood, so that even if the top buds on the old wood get blasted by the cold, the bottom ones have a chance of flowering.
So says Michael Dirr. He also says that his newest reblooming hydrangea, the one called BloomstruckTM, is the best rebloomer to date and is, “… exceptionally stem hardy. Survived 50 days below zero with a low of -28 degrees in Bailey’s trial nursery area in Minnesota.” He goes on to say that while it was being tested in the same trial area it was killed to the ground, but regrew the next spring and had flowers on every terminal by June. Nothing like that happened here with our Endless Summers. Mine never even saw a flower until September.
Which brings us finally to the reason why I am writing about hydrangeas in the second week of December. No I’m not crazy.
Yes, you maybe should wrap your hydrangeas to protect them from the upcoming winter.
This is not something I’m used to saying, but after last winter, I’m giving it a strong thumbs up. There was only one gardener out here in the Hamptons that I know of who had flowers on all the hydrangeas in all his gardens this year, and that was a gentleman who used Wilt pruf on all his hydrangeas’ buds and then wrapped each and every one of those Wilt prufed plants in all of his clients’ gardens in burlap.
I’ll be honest, I’m not going to do it in my garden because I don’t have the time to do it, nor can I afford to pay someone to do it for me, but if I could, I certainly would, and I’d like to recommend to you to do so.
Now luckily for me, this year we’ve had a long, slow cool down. It’s not the sudden drop we had last fall, followed by high temperatures and then a long, cold, deep winter, so this year the plants have had a better chance to acclimate, but we shall have to wait and see. It’s actually the abrupt up and downs, the days that rocket down from high 40’s to low 60’s degree afternoons to low 30’s and high 20’s at nights that do the most damage to plants.
And I know that everyone keeps talking about how unusually cold this past winter was, but when I was a kid Mecox Bay froze solid enough each winter for us to ice boat across. An iceboat is a sailboat on enormous ice skates, so that meant the bay was not just skinned with ice; it was deeply, solidly frozen.
I also know that everyone had a more diverse garden when I was a kid, there were weigelas and kolkwitzias and spireas and viburnums and hydrangeas. No one just used a mass of hydrangeas to give them color and nothing else, so if it was really cold and there were no hydrangea flowers there were other ways and means to have color in your gardens. Of course this was when people were also doing more with perennials, a phase that seems to have passed, but that’s all for some other conversation. I actually don’t think it was that unusually of a cold winter, I just think we all got lulled into thinking those incredibly hot summers were the norm.
Don’t you remember when we were kids? No one had air conditioning then, and we all were fine with fans. Maybe there were 4 or 5 killer nights when you wanted to sleep on the porch, because the house was too hot, but AC was not a fact of life. So maybe last year was an anomaly, and this winter will be mild again and next summer will be a scorcher. Or maybe not. I actually have no idea. Nor does Michael Dirr. We asked his advice and he sent my colleague a presentation from one of his associates, Mal Condon who owns Hydrangea Farm Nursery in Yarmouth Port, MA.
He suggests you wrap your hydrangeas.
Paige Patterson was planning on buying a few more bulbs now that they are on sale, but she’s coming down with a terrible cold.