The conventional answer is that it depends on which of the two types of hydrangea you are talking about. The Macrophylla Hydrangeas bloom on old wood and the Hydrangea paniculata and Hydrangea arborescens families flower on new wood. Prune old wood immediately after flowering and new wood in the fall, but it’s not quite as simple as that as Mike McGroarty explains in an article I found on Mike’s Backyard Nursery website.
Hydrangeas are?confusing to say the least, but in this article I am going to set the record straight and simplify your gardening life.??For the most part Hydrangeas fall into two categories.? Those that flower on new wood, and those that flower on old wood.??Simple enough right?? Not?really.? Then to make matters worse there are those that bloom on old wood and new wood.
Hydrangea Endless Summer is one that blooms on both old wood and new wood.? It blooms all summer long.
The Nikko Blue Hydrangea is in the Macrophylla family of hydrangeas and for the most part, but not always, Macrophylla Hydrangeas bloom on old wood.? So what does that mean?? What is old wood and what is new wood?? And should I care.? No, I really don?t think you should care.? It?s just to confusing to keep it all straight.? But for the record, I?ll show you some old wood and some new wood and explain why the gardening community makes such a big deal out this.
Look to the bottom left of the above photo.? See where I made the cut to remove this branch from the plant?? I made my cut into old wood.?? Then if you follow along from where I made that cut over to the bottom right of the photo you?ll see where the new growth starts.? That?s the beginning of the new wood.? Notice how it?s light green in color?? It?s also softer and more pliable because it?s new growth from the current growing season.? As the season progresses and we get closer to winter this new growth begins to harden off so it?s durable enough to withstand the winter weather.
I should note, just for the record, that I took this photo on July 2nd.? The old wood that you see in the photo was from last years growing season.? The new wood of course is from this years growing season.? Why does it matter?? I?m glad you asked.
Some hydrangeas, many in the macrophylla family, start producing flower buds this summer for the following year.? So if you prune your hydrangea too severely late in the season you are likely to cut off many if not all of the flower buds for next year.? Same thing with Rhododendrons, Azlaeas and some other plants.? So ideally you should prune them right after they bloom then leave them alone.? However, with Hydrangeas that?s not easy to do because the new varieties like Endless Summer can bloom well into the fall.?? Hmmmmm.? That?s a problem.
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