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.
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.
Hydrangea species that bloom in early spring should be cut back just after they finish flowering in May or June. Those that bloom in the summer should be pruned while they are dormant in December through February. Dead wood can be removed at any time of the year.
In general, plants should be pruned to improve appearance not control size. I repeat that because it's important: Hydrangeas should be pruned to improve appearance, not control size. The mature hydrangea is a shrub that cannot be made smaller.
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.
If you don't prune hydrangeas then they can eventually resemble a tangled mass of woody stems, and the flowers will become smaller and less showy.
Old Wood Bloomers
Hydrangeas that bloom on old wood do not need pruning and are better off for it.
Sometimes bigleaf hydrangeas become overgrown and need to be trimmed. However, too much pruning will greatly reduce or eliminate flowering. In late summer, after the bloom period, dried flowers can be removed.
' Much like the issue of when to plant hydrangeas, transplanting them is best when they are dormant. In a cooler climate, this is most commonly during the fall, but in warmer areas, you can often transplant them over winter, as long as the ground isn't frozen.
Trimming should be done immediately after flowering stops in summer, but no later than August 1. Do not prune in fall, winter, or spring or you could be cutting off new buds. Tip-pruning the branches as leaves emerge in spring can encourage multiple, smaller flower heads rather than fewer larger flower heads.
Removing spent flowers will ensure your hydrangeas produce healthier, more bountiful blooms later on.
The most common reason Hydrangeas get woody is weather-related. During periods of harsh winter weather, stems can become damaged. These stems die, leaving you with unsightly bare sticks in the spring and summer—a far cry from the lush shrub that you had imagined for your landscape.
Regardless of the type of hydrangeas you're growing—and whether it blooms on old or new wood—the cutting process is the same. Start by using clean, sharp shears, then make your cut. "Cut stems above a node, and include at least two leaf groups on the cut stem," says Godshalk.
However, stop deadheading hydrangea shrubs in mid to late fall, leaving any spent blooms in place. This not only provides winter interest, but also ensures you don't remove the buds that will become flowers next spring.
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. In addition, fruit peels, lawn clippings, peat moss and pine needles, are thought to have a similar effect.
In cooler climates, the best time for moving hydrangea bushes is November, when the bush is dormant but the ground is not yet frozen solid. In warmer climates where the ground doesn't freeze, you can do your hydrangea transplanting between December and February.
Many horticulturists recommend root-pruning a hydrangea a few days before transplanting.
Spring and fall are fine for planting hydrangea bushes; most sources I found recommend waiting for cooler weather and transplanting the bushes in late fall or very early spring while the plants are dormant but the soil is workable.
Other times, you might need a fork or shovel to help divide the plant. Either way, once you have two pieces with roots attached to each, you now have two plants to replant. The best time to divide bigleaf hydrangeas is very early spring, just as new green buds are starting to swell and open along the stems.