The real reason most people go to a hydrangea lecture is not to find out about all the different cultivars, and all the different ways you can use these magnificent plants in the landscape, nope, the real reason they come is to ask when and how they can prune their big blue, big leaf (macrophylla) hydrangeas. I probably get asked that question about forty times a week every spring. I’ve thought about wearing a shirt that has the short but sweet answer printed in red, but the truth is, the answer isn’t one people want to hear so I have to explain it to everyone each time. And since no one really wants to believe me, I sometimes have to explain it twice. Here’s the short answer to the question of when can I prune my hydrangeas.
See, I told you that you weren’t going to like it.
The truth is that most people have huge, mop head flowering big leaf hydrangeas planted around the foundation of their homes and they’ve grown so much in the 10 years since they were planted that they’re now covering the windows. These same people either whacked their hydrangeas back, or had their gardeners cut them back, or one of the couple is more fastidious then the other, and someone wanted to see out the windows and guess what? Those plants had no flowers the following season. Invariably there was an argument over who did what when, or who’s to blame and now that couple, or that gardener, or that individual would come to our lecture asking us to tell them when the correct time to cut their hydrangeas, so they can have shorter plants with just as many flowers. The problem is they can’t.
Most Hydrangeas macrophylla bloom on old wood. This means they set their beds in the fall on branches that grew up this spring, and that next spring, these buds are the ones that flower. Which translates into “please don’t touch the dead looking brown sticks that are looking so gangly and unattractive in the winter since this is where next years flowers are sitting and waiting out the winter.”
Got it? Good, but in my experience everyone says they’re got it, but their brains just haven’t really accepted the truth so, what I do during the lectures is that I manhandle a plant up in front of everyone and I show them the bud that’s forming at the base of each leaf. I make them touch the bud and then I explain that the bud under their finger is the same bud that’s going to grow the branch with next years flower and the end and that for each bud that gets pruned off, that’s how many fewer flowers they’re going to have next year.
It is at this point that a few of them start to get it.
Of course this is also when someone always tells us how he or she has an uncle or a neighbor or a family friend who cuts their hydrangeas each year and always gets flowers and I say, “Fantastic! Here’s the deal, I want you to try and get that uncle/neighbor/family friend to come over to your house and cut yours too, since there are always exceptions to all rules.” I also tell them I know people who have had success by cutting back their hydrangeas before next years flower buds are set, but that means they are pruning hydrangeas in July which, for me, sort of defeats the whole purpose of having hydrangeas to begin with.
The more you cut, the less flowers you’ll have is the rule, I tell them for every hydrangeas that blooms on old wood. “But my hydrangeas are flopping over!” someone will yell or, “but they’ve gotten so big, you must be able to do something!”
So I tell them about rejuvenation pruning, a technique where you prune a plant back hard, to let it start all over again, and I tell them how my experience with my hydrangea. This sucker was 8’ tall, no exaggeration and flopped all over the place, and since I had planted it right next to the steps to my kitchen door, it made entering and leaving the house a real challenge. My husband had started to call it the bondage hydrangea based on how I resort to was using garden twine to try and pull it up and back with loops that tied it to the railings of the porch behind it and that each year I was using more and more twine. So I whacked that plant totally back to the ground, assuming that the following year it would be smaller and more manageable. I knew that I’d have no flowers, which I didn’t, but what I didn’t guess was that the next year, my mature hydrangea would send up new shoots that were close to 7’ tall and guess what? No flowers! So again, I could not get in or out of the house.
We prune plants to improve their shape and the way it fits into the landscape, we prune for health and to make a plant appear either balanced or unbalanced depending on your desire, not to control size, unless we are talking about privet. And privet that is pruned doesn’t bloom. If you want hydrangeas that stay shorter, you should invest in one of the newer dwarf varieties like the Citiline cultivars that max out at 3 or 4 feet. I happen to adore the cultivar called Berlin and replaced the bondage hydrangea with one last year.
I know that no one wants to hear about having to change all their hydrangeas, I understand, but if you have Nikko Blue’s, the most common, old fashioned big blue mopheads that you see everywhere, you could end up without flowers even if you don’t prune, since with the crazy weather we’re having lately there’s a good chance your hydrangeas' buds are going to start opening since the plants just can’t tell when winter is over and sometimes mistake our warmish winters for spring only to be shocked when the cold descends like a hammer.
Which is why the best time to prune the old growth hydrangeas is in the spring, when the leaf buds have started to open. It makes it so much simpler if you can see which ones made it through the winter and which ones need a little reshaping to deal with dead wood or to reshape because one branch is three times longer than all the others, or there’s a little tuft of green leaves flailing away a foot higher then the rest of the plant. At that time it’s also easy to see which of the old brown sticks are dead wood and can be removed completely to make room for new growth. The neatniks in the audience don’t like it, they tell me those brown sticks look unattractive all winter long, so I tell them to get a little twine and tie them into bundles, or avert their eyes or get a different plant, since this is what hydrangeas are all about.
It's also why people are so excited about the hydrangea called Endless Summer. A famous plant breeder and plantaholic named Michael Dirr was visiting a nursery in St. Paul, Minnesota in September, and saw, in a block of hydrangeas, one that was covered in big, new blue blooms while all the others were over and done and faded. He immediately knew this was the holy grail of hydrangeas, a remontant hydrangea, a plant geek word that means this plant had the ability to bloom more than once, since unlike the other old fashioned varieties of big leaf hydrangeas, this one was blooming on both old and new wood at the same time. Dirr recognized the importance of this plant since not only would it keep flowering much longer then it's regular brethren, but since it also had the ability to create new buds on new wood, if it's old ones were pruned off by mistake or if they were killed by weirdly fluctuating temperatures, this plant could still produce flowers. He immediately got the plant patented and it became the queen of all hydrangeas, a seriously important plant and pretty much the only plant most people to buy if they’re looking for a big pink or blue mophead hydrangea. Yes you can prune it, but you will delay flowering and have fewer flowers in the spring, however if you dead head it, it will keep going significantly longer then your Nikkos do.
Of course, since that plant has come out there’s been another new introduction called Mini Penny. This is a dwarf Endless Summer. It’s maximum height is supposedly 3-4-5 feet we don’t actually know yet, since it’s so new, but since it blooms on both old and new wood, and will rebloom copiously if dead headed, it seems like it will be the plant of the year out here. I recommend you rush out to your favorite nursery and buy a boatload full.
But then again, we all know I have a bit of a plant-purchasing problem.
Paige Patterson has a new variety of hydrangea, called Everlasting riding around with her in the back of her car. She’ll be sneaking onto her property soon.