The best advice for hydrangeas is to consider their mature size. Locate them in an area they won't outgrow and require heavy pruning to keep them in bounds. Hydrangeas do not require strict reqular pruning; simply keep them healthy by removing dead wood and they will grow and flower well.
When to prune hydrangeas. Most pruning is carried out in late winter or early spring. However, the climbing hydrangea is pruned after flowering in summer.
Prune these hydrangeas only after bloom in the summer and not in the fall. Old wood hydrangeas start developing their bloom buds for next year in August and September. If you don't prune your hydrangeas real soon, then it is better to wait until next year. Otherwise you won't have any blooms next spring.
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.
Cut back any clearly dead branches, which are brittle and snap off easily. This can be done in the fall or any time you see a dead branch. 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.
Hydrangeas that bloom on new wood can be safely pruned in late fall once the plants have gone dormant or in early spring. Next year's flower buds won't be formed until late spring the same year they bloom, so there is no risk of removing the buds if you prune in fall or spring.
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.
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.
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.
Deadheading your hydrangeas isn't a care step you want to skip. "Deadheading allows the energy produced by the plant to go into the leaves, stems, and roots (rather than forming seeds) for future growth," says Melinda Myers, a professional gardener.
Look at the foliage to identify your type of hydrangea. Mountain hydrangea foliage has serrated edges that are often tinted maroon at the edges. The round hydrangea flower form comes in what is called a mophead or lacecap version. The lacecap flower has outer petals that surround the pollen capsules in the center.
Most common hydrangeas prefer a partial sun location - ideally receiving sun in the morning hours and shade in the afternoon. The reblooming Endless Summer® Hydrangea series prefers part shade.
In late winter or early spring, these shrubs can be cut all the way back to the ground. Smooth hydrangeas will produce much larger blooms if pruned hard like this each year, but many gardeners opt for smaller blooms on sturdier stems.
Keep Them Cozy. Whether or not hydrangeas need protection depends on how cold the winter temperatures drop. If the air temperature doesn't go below 0 degrees (zone 7) there is no need for winter protection. In colder climates, wrap or completely cover marginally hardy hydrangeas.
To prepare hydrangeas for winter in colder areas, add a thick layer of mulch around the base of the plants to protect the crown and roots from freezing temperatures.
Mophead hydrangeas look lovely in the fall when their blue, purple and pink flowers contrast with the fall foliage. Brown flowers can be snipped off if they annoy you, but you don't have to remove them. Look for flowers like this to dry or for making Hydrangea Wreaths.
Some hydrangeas bloom on new growth and should be pruned in late winter or early spring, before the shrub begins active growth. These include several varieties that have become quite popular: Limelight, Quickfire, Burgundy Lace, as well as the classic "snowball" types, such as Annabelle.
The primary reasons hydrangeas don't bloom are incorrect pruning, bud damage due to winter and/or early spring weather, location and too much fertilizer. Hydrangea varieties can be of the type that blooms on old wood, new wood or both. Old wood is the current year's growth and new wood is next year's (spring) growth.