Hydrangeas are colorful and relatively low-maintenance plants to work into in your landscape. They grow best in zones four through nine. Although it’s not exactly necessary to prune them annually, you'll still have to sharpen your shears if you intend to shape or groom these plants in any way. Depending on the type of hydrangeas you have in your garden, now may be the best time to prune them. You’ll not only maintain the shape of your plants, but you’ll also improve their health and encourage fuller, more vibrant growth.
What Kind of Hydrangeas Do You Have?
Hydrangeas fall into two general categories: those that bloom on old wood and those that bloom on new wood.
Old-wood-blooming varieties include bigleaf, mopleaf, lacecap, and oakleaf hydrangeas. Their stems begin to develop the following year’s growth as soon they’ve finished blooming for the current year. These plants should only be pruned in the late summer after they’ve flowered for the year. Doing so in the winter months will impact the number of blossoms you see later on. Prune as the flowers fade, but do it early enough that the plant has time to recover and begin the process of producing next year’s growth. Try to prune the older stems first so that the new growth has a chance to get air and light. Make sure to remove the oldest branches and any branches that aren’t producing.
Although old-wood-blooming hydrangeas should be planted in a spot where they'll have plenty room to grow, a good pruning every five years or so will give them a much-needed vitality boost. To prune them, simply cut below the spot where the blossom meets the cane.
New-wood-blooming hydrangeas develop flowers on the new growth of the current year. They often bloom later than old-wood-blooming varieties. New-wood-blooming varieties include panicle hydrangeas and smooth hydrangeas.
It's important to note that there’s also a third type of hydrangea that falls somewhere between the first two. Endless blooming hydrangeas grow on both old and new wood. They bloom early in the year and then again later on, producing flowers all summer long. Since you may not need to prune these plants unless you want to change their shape, you’ll likely only deadhead them. Remove any faded flowers and cut the stems down to half their length. If you do decide to prune, wait until the fall months for the best results.
Pruning New-Growth Hydrangeas
The best time to prune new-growth-blooming hydrangeas is in the late winter, before the plants emerge from dormancy and start to send out new growth. Cut the stems back by a third to help them produce bigger flowers. Remove dead canes and crossing branches to improve airflow.
If giant flowers are what you desire, don’t be shy about cutting them down to the ground. A hard pruning will allow the flowers to develop larger blooms. Just make sure to leave some old canes in place to help the plant maintain its shape and strength — and to keep the flowers from flopping over.
Keep in Mind...
Hydrangeas don’t always need to be pruned. New-wood-blooming plants will blossom regardless of whether or not you bring out the shears. Of course, pruning does promote more vigorous growth. While a hard prune will help them come back with a vengeance in the spring, it may also weaken the plants if done every year.
Be sure to keep your pruning shears clean as you trim. Soak a cloth in denatured alcohol and wipe the blades clean as you go.
What About Climbing Hydrangeas?
Climbing hydrangeas don't require much pruning unless you wish to cut them back for shape maintenance. Prune them just after flowering, trimming the previous year’s growth down to one or two inches and removing any shoots that have been pulled from their supports.
Oh No, I Pruned Too Much or at the Wrong Time!
Don’t worry. If you get overzealous with the pruning shears, your hydrangeas will recover. They may not produce a ton of blossoms this year, but they’ll recover if you give them the right amounts of sunlight and water during the year and stay away from the shears next year. Your hydrangeas will return to their former glory. Plants are typically very forgiving, and as long as you give them some basic care, no one will ever know you went a snip or two too far. The might even come back bigger, better, and more vibrant than before.