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Don't do it or you'll risk cutting off the flower buds. Pruning your hydrangeas to reduce their height isn't effective because they will grow right back to their original size, or even larger because the act of pruning stimulates new growth.
To rejuvenate the hydrangea, remove up to 1/3 of the older living stems down to the ground each summer. This will revitalize the plant. If necessary to control the size of the plant, cut back before late July to allow for buds to develop. Usually the plant will return immediately to its former size.
"When to prune these woody-stemmed hydrangeas is not as critical as [with old wood] varieties, as long as you avoid pruning when the flower buds are opening," says Becker. Trim in early spring, before the flowers begin to bud, or after the plant has finished flowering.
Reason #3 – You Have a Panicle or Smooth Hydrangea
Panicle Hydrangeas (H. paniculata) include PeeGees, and Smooth Hydrangeas (H. arborescence) include Annabelles. These new wood bloomers can be pruned to the ground each fall and come back in the spring with lush foliage and beautiful blooms.
In addition to bolstering future blooms and strengthening stems, deadheading your hydrangeas has aesthetic benefits, too. "Removing faded flowers creates a neat and tidy appearance, which many gardeners prefer over the look of leaving dried flowers on the plant," says Meyers.
(3) In addition, if it becomes necessary to prune a plant to reduce its size, it may be cut back in June or July without harming the next year's bloom. But it will return almost immediately to it's former size.
If your hydrangea is too wide for the location, you can dig it up and divide the plant, or move it back away from driveways and walks. If just a few stems are hanging into walkways, follow those to the ground or where they join another stem, and cut them off.
To reduce the size of a hydrangea that blooms on new wood, cut off about one-third of each stem in late fall or early spring before it begins to leaf out. If your hydrangea blooms on old wood, prune right after it has bloomed when the flowers are fading.
Without going through the deadheading process, hydrangeas will not produce as many flowers and the few produced may not grow as big to their full potential.
While some plants bloom on new growth, others primarily set flower buds on old wood. Regardless, it is best to wait to prune all hydrangeas until spring. In the fall, hydrangeas (and all trees and shrubs) are in the process of going dormant. They do not produce very much new growth until the following spring.
Wrap with winter protection.
During the winter, make a DIY A-frame wire cage out of burlap and chicken wire to protect your hydrangea plant. This cage will protect it from winter winds, heavy snowfall, and cold temperatures.
Know when they're beyond repair.
If you catch and treat your hydrangeas when their blooms first start turning brown, Myers says there's a good chance you'll be able to turn them around (as long as it's not due to weather damage). "However, once they turn fully brown, there's not much you can do," she says.
As soon as hydrangeas are cut, the stems should immediately be put into tepid water. And adding a little bit of flower food to it would be a great idea too. Use a sharp knife or clippers to cut each stem on a diagonal and submerge! Cut hydrangeas in the morning and choose only the most mature blooms.
So the bottom line is that if a hydrangea is too large for the location where it has been growing, the best thing would be to move it and plant a smaller variety in that spot.
Brown, tan, yellowish or black spots on hydrangea leaves may be anthracnose. You can also identify it by cankers that form on stems and branches. Anthracnose can be fatal to hydrangeas, so prune out dead or diseased plant parts and destroy them.
Some gardeners report success in turning their hydrangeas blue by applying coffee grounds to the soil. The coffee grounds make the soil more acidic, allowing the hydrangea to more easily absorb aluminum.
You can also check your hydrangea in the fall to see if any buds are starting to push out already. If there are buds already on the branches, then it blooms on old wood. If there are not yet buds in the fall, then it will push them out on new growth the following spring.
You should deadhead throughout the blooming season to keep your hydrangeas looking their beast and encourage new flower growth. However, stop deadheading hydrangea shrubs in mid to late fall, leaving any spent blooms in place.