Panicle hydrangea needs to be pruned in early spring
Yes, it’s time to prune new wood hydrangeas. Now that it is mid spring and your hydrangeas are dormant or just beginning to leaf out, this is the time to get those clippers out for some of them. When I say some, I mean those that bloom on new wood, the growth they will put on in the current season. In the late fall when they still have their leaves, wait until they are leafless and have gone completely dormant before you cut them. You can also do this pruning in winter when they are fast asleep.
WHEN IS THE RIGHT TIME TO PRUNE NEW WOOD BLOOMING HYDRANGEAS
It is critical for pruning new wood hydrangeas that you wait until all growth has stopped. That’s because pruning always stimulates a plant. If you prune while there are still leaves on that plant, it will continue to grow and possibly start producing the buds for flowers you want next year. That means in a cold winter climate those flowers might not survive and you will be the one to blame for that. Just wait it out and let the plant go into its rest cycle. Then you can cut it back as needed.
If you want to know about pruning other hydrangeas, see my prior pruning post. I cover pruning big leaf hydrangeas, mountain hydrangeas, oak leaf hydrangeas, and climbing hydrangeas.
WHICH HYDRANGEAS BLOOM ON NEW WOOD
I am talking here about 2 species of hydrangeas: hydrangea arborescens (woodland or smooth), e.g., ‘Annabelle’, Incrediball®, Invincibelle® Spirit, ‘Haas‘ Halo‘, and White Dome®, and panicle hydrangeas (PG), e.g., Little Quick Fire®, Pinky Winky®, Vanilla Strawberry™,Quick Fire®and ‘Limelight‘.
THE RIGHT TOOLS TO PRUNE NEW WOOD HYDRANGEAS
Before you even start, however, make sure you have the right tools including some kind of disinfectant. You don’t want to unknowingly spread disease as you move from plant to plant. A simple spray of rubbing alcohol (70%) from the drugstore is all you need to protect your plants or your desired disinfectant of choice. Just make sure you do it.
The right tools to prune new wood hydrangeas
Basic pruning rules apply to all hydrangeas. Take care of the 3Ds: Dead, Diseased, and Damaged wood. It has to go. Next remove any stems that are crossing and growing inward. Look at this example of an inward growing branch of a hydrangea paniculata. It rubbed all winter long and left a deep cut in both stems which now have to go. If not, it will allow insects and disease easy entry into the plant.
Wounded stem from rubbing needs to be removed.
PRUNE NEW WOOD SMOOTH/WOODLAND HYDRANGEAS
Since the arborescens will bloom first, let’s start there. For strong stems, you would be wise not to take them down too far, especially the mophead versions as rain will saturate the flowers and make them droop . Your best bet is to cut the stems no lower than 18″. You could even go as high as 3-4 feet or just simply deadhead the spent flowers. But if the stems have been bent from the weight of heavy wet snow, cut them below the bend: you don’t want to start the season with a bent stem which will surely cause a floppy flower.
Woodland hydrangea after spring pruning
PRUNE NEW WOOD PANICLE HYDRANGEAS
Next prune your panicle hydrangeas. According to a study done at the Chicago Botanic Garden, they respond well when cut by one half so don’t be shy. Just get to them before they set up their flower buds. You don’t need to be conservative with this species; they are vigorous growers and will regenerate in response to your pruning.
Panicle hydrangea needs to be pruned in spring.
Panicle hydrangea after spring pruning
If your panicle hydrangea is on a standard (single trunk) and looks like a lollipop, cut to maintain that rounded top shape. Eliminate all growth on the main trunk and suckers at the base. You can prune as much or as little as you want.
OTHER MAINTENANCE TO DO NOW
Once you have finished pruning, take the time now to apply the appropriate fertilizer (NOT 10-10-10), check your irrigation if you have that, and reapply the correct mulch for each species (NO volcanoes).
WHAT NOT TO DO
I can’t emphasize enough if you cut either of these 2 species in the fall when they still have their leaves, you could be in trouble. Pruning them when they are about to go dormant sends them the wrong message and potentially robs you of the following year’s flowers. Don’t do it.
GET MORE INFO ON PRUNING HYDRANGEAS
Hydrangea book with lots of info on how best to grow these shrubs.
