About Panicle Hydrangeas
Panicle hydrangeas (Hydrangea paniculata) include PeeGee hydrangeas and ‘Limelight’ hydrangeas.
Flowers on panicle hydrangeas are panicle-shaped (cone-shaped), in contrast to the ball-shaped mopheads or flattened lacecaps. Blooms start out white or cream colored but as the flowers age, they take on a pinkish tinge. Blossoms will often dry out and hang on to the shrub throughout the winter, adding interest to the winter garden. If you don’t like the look, you an easily prune off the browned flowers.
H. paniculata often grows quite large. Unless it is grown as a tree-form hydrangea, it will often grow up to 8 or 10 feet tall and wide.
These types of hydrangeas do well in a wide variety of climates and are one of the few hydrangeas that will bloom in colder climates, even as far north as Zone 3.
They need at least a few hours of direct sun to do well and will often bloom best in full sun. This is quite different from mophead hydrangeas which prefer only a bit of sun (usually in the morning only). Consider growing H. paniculata if you have a sunny garden or live in zone 5 or colder.
When to Prune Panicle Hydrangeas
These types of hydrangeas bloom on new wood. This makes them one of the easiest hydrangeas to prune as they can be pruned almost any time of year, except summer. They usually bloom in late summer so if you prune them at this time of year you’ll end up cutting off most of the flowers.
Many gardeners prefer to prune in late winter – it’s easier to see the branch structure and reach into the interior of the shrub when there are no leaves on the plant.
Panicle hydrangeas do not need to be pruned every year but, as a general rule of thumb, removing about 1/3 of the oldest branches each year will make for a fuller and healthier shrub.
Why to Prune Panicle Hydrangeas
You would normally prune panicle hydrangeas for the following reasons:
- to create a more pleasing shape,
- to control growth,
- to remove dead flowers,
- to remove crossing branches, or
- to eliminate dead, damaged, or diseased stems.
Tree Form Panicle Hydrangeas
Panicle hydrangeas are unique in that they are the only type of hydrangeas that can be pruned into a tree-form.
The process of training a panicle hydrangea into a tree starts when the shrub is young. This is usually done by the grower or nursery, rather than by the home gardener – you can buy tree-form shrubs from the nursery.
Once the tree shape is established, pruning must be done regularly to maintain the proper shape. If you skip pruning for even one year, the tree top can get so large that the branches bend all the way to the ground! Once the branches are overgrown, it’s very difficult to prune the shrub back into a proper tree form. This makes the tree form panicle hydrangea more high maintenance than other hydrangeas in this group.
Be careful not to prune out the main top branches or to cut the trunk – this will cause the hydrangea to put out new growth at the base and the tree shape will be lost.
- When to Prune Hydrangeas
- Five Reasons to Prune Hydrangeas
- Five Questions to Ask Before Pruning Anything