DEADHEADING HYDRANGEAS: THE DETAILS

This is the time of year when many gardeners wonder about deadheading their hydrangeas. Like everything else about this shrub, what you do depends on the type of hydrangea you have and what you want to achieve. Let’s dig down into the details.

DEADHEADING BIG LEAF AND MOUNTAIN HYDRANGEAS

If you have a big leaf (macrophylla) or mountain (serrata) hydrangea with faded flowers, and you want to neaten it up, go ahead and make the cut just above a pair of leaves. Look closely: you will see leaves just below the flower. Go a little further down to where 2 leaves are opposite each other. That’s where you make the cut.

Where to cut big leaf hydrangea flower when deadheading

Big leaf hydrangea flower after being deadheaded. Note those first leaves remain on the stem that has been cut.

This can be especially beneficial if your plant is a rebloomer as this cut will continue to stimulate the plant to make more flowers this season. If the plant is NOT a rebloomer, you will still be stimulating it to do its thing for the remainder of the season. That means your cut will encourage it to make new stems and, therefore, more flowers for next year.

WHEN TO DEADHEAD BIG LEAF AND MOUNTAIN HYDRANGEAS

Try to make your cuts before August 15 (in the Northern hemisphere) as you don’t want to stimulate your plant too late in the season. Keep in mind that these plants set their flower buds for next year on short day length (now in the Northern hemisphere) and when night temps are consistently below 60 degrees F. Depending on where you live, that can be early August or later into the fall.

WHY YOU SHOULDN’T DEADHEAD YOUR BIG LEAF AND MOUNTAIN HYDRANGEAS

If your spent flowers aren’t making you crazy, you can just leave them on the plant until next spring. Those faded flowers can serve several purposes. First, as they fade, they can morph into lovely colors. That’s known as “Antique Season” for hydrangeas. I did a post on that last year which you can read HERE. Also, keep in mind that faded flowers can provide winter interest in what can be an otherwise bleak landscape. Lastly, those faded flowers act like umbrellas and protect the lower parts of the plant from what Ol’ Man Winter might dish out.

DEADHEADING OTHER HYDRANGEAS

If you want to deadhead your woodland/smooth hydrangeas (arborescens) and your panicle (paniculata) hydrangeas, go for it. They flower on new wood so you can freely cut them. Keep in mind that cutting will stimulate your plant and encourage it to develop new growth. That energy would be better spent keeping the plant “quiet” as it gets ready to go dormant for the winter. The new growth it might push as a result of your cutting might not make it through the winter, so why bother? Plus, as mentioned earlier, those faded flowers in winter can add interest to your winter views.

Climbing hydrangeas are better left untouched after August 1. The same goes for your oakleaf (quercifolia) hydrangeas at this point. Take time to enjoy the flowers as their colors deepen to rose in some cases. The foliage of your oak leaf hydrangea will come into its own as it morphs into a deep wine color.

WHAT ABOUT CUTTING HYDRANGEAS FOR BOUQUETS

Cutting fresh flowers for bouquets is definitely on your agenda for late July. The flowers can grace your home or office in any number of ways. Maybe a bouquet will brighten up someone else’s day. For those bouquets, you will probably cut further down on the stem. Just be sure to cut above a pair of opposite leaves as already discussed.

UPCOMING PUBLIC TALKS

Audience listening to speaker

I have an in-person hydrangea class at the New York Botanical Garden in August. We spend 2 hours in the classroom and the third hour walking through the garden where we “connect the dots.” You’ll see what the various plants look like in a garden setting, and we discuss a variety of maintenance activities for these beauties.

I am also booking Zoom/virtual talks as well as in person presentations. If your organization wants to discuss these possibilities, use the “Contact Me” tab on my site.

Here’s to happy hydrangeas — and gardeners!