HYDRANGEA PRUNING - WOODLAND AND PGs
In my April Connecticut garden, the first hydrangeas I'm pruning are the ones that flower on the growth they will put on this year, better known as "new wood." In hydrangea-land, those are hydrangeas arborescens or woodland/smooth hydrangeas like 'Annabelle', or for example any plant that has Incrediball® or Invincibelle® in its name. There are many others. They will all have "arborescens" as the second part of their name. The flowers are round and either white or shades of pink. None are blue and you can't change their color.
You can prune these plants whenever they are dormant, i.e., after they drop their leaves. That could be in late fall, winter, and now, early spring. Take it down to about 2 feet. If you cut it to the ground or to its crown as I have seen on various websites, you will wind up with weak stems. The flowers will bend over and the plant will flop during the season, especially after rain. Those magnificent flowers hold water which will weigh them down - they need strong stems to keep them erect.
This is what one of my Annabelles looked like before I pruned it. Notice the stems aren't bent from the winter weather in my snowy zone 5.
The second group of hydrangeas that flower on new wood are the panicle hydrangeas,sometimes called PG. These have flowers that are cone- or football-shaped, start out white or lime green and age to shades of pink and rose. You might know them as 'Limelight', Quick Fire®, Vanilla Strawberry™, 'Fire and Ice', and dozens more.
Just like the arborescens, you can prune these plants whenever they are dormant, i.e., after they drop their leaves. That could be in late fall, winter, and now, early spring. Cutting them by about one-third is the general recommendation. But that's not always the case. For example, if you grow 'Limelight' and want to prevent it from flopping during the season, take that one down to about 4 buds. That will strengthen the stems to better hold the flowers upright.
After I cut the tall stems, took out others that were crossing and growing inward, and those that were thinner than a pencil, it emerged looking like this:
You may not have time for this extensive pruning. Know, however, that pruning makes your plant healthier, stimulates new growth, and will give you stronger stems and better flowers if you do. If you don't prune and don't deadhead, here's what happens:
Your plant will flower anyway. Notice, though, that the new flower is very small compared to the dead one to its left which of course, you should remove now. The lesson is: minimally you should deadhead your plant and for best performance, do a thorough pruning job.
Make sure as you move from plant to plant that you disinfect your cutting tools. You don't want to unintentionally move pathogens around your garden. Disinfecting is easy. You can use Lysol® spray on your tools to get into the crevices which can harbor the invisible germs. Studies prove it kills most germs in an average home garden. Your other choice is to make a spray of a 10% solution of rubbing/isopropyl alcohol from your home medicine cabinet using a spray bottle from the dollar store. Don't forget to wipe down your gloves/hands.
You're probably wondering what to do about your other hydrangeas: bigleaf, climbing, oakleaf, and mountain hydrangeas. They all flower on wood that grew last year, i.e., old wood. Unless you want to remove this year's flowers, the short answer is don't touch them. You are in the HYDRANGEA DANGER ZONE™. But it's not that simple.
I'll be posting about what to do with them in the next few weeks. If you can't wait until then, you can go back to my 2018 posts when I wrote about this same topic. It never gets old. OR you can attend one of my 2 upcoming classes on hydrangea pruning:
April 16: UConn Master Gardener Program, Bethel CT
Topic: Pruning Hydrangeas: Let's Do It Right! 1-3 p.m., fee
April 27: New York Botanical Garden, Bronx NY
Topic: Pruning Hydrangeas: What Stays, What Goes, and When 10 am–1 pm, fee
Pruning new wood hydrangeas is something you can master with a little time and attention. You'll find them forgiving even if you make a mistake or two. Just be sure you prune them before they are too far along for this season or you'll miss your window.
You can prune these plants whenever they are dormant, i.e., after they drop their leaves. That could be in late fall, winter, and now, early spring. Take it down to about 2 feet. If you cut it to the ground or to its crown as I have seen on various websites, you will wind up with weak stems. The flowers will bend over and the plant will flop during the season, especially after rain. Those magnificent flowers hold water which will weigh them down - they need strong stems to keep them erect.
This is what one of my Annabelles looked like before I pruned it. Notice the stems aren't bent from the winter weather in my snowy zone 5.
 |
| Hydrangea Arborescens Annabelle Before Pruning |
Here's what it looked like after pruning:
 |
| Hydrangea Arborescens Annabelle After Pruning |
The second group of hydrangeas that flower on new wood are the panicle hydrangeas,sometimes called PG. These have flowers that are cone- or football-shaped, start out white or lime green and age to shades of pink and rose. You might know them as 'Limelight', Quick Fire®, Vanilla Strawberry™, 'Fire and Ice', and dozens more.
Just like the arborescens, you can prune these plants whenever they are dormant, i.e., after they drop their leaves. That could be in late fall, winter, and now, early spring. Cutting them by about one-third is the general recommendation. But that's not always the case. For example, if you grow 'Limelight' and want to prevent it from flopping during the season, take that one down to about 4 buds. That will strengthen the stems to better hold the flowers upright.
Here's ‘Limelight’ before pruning:
 |
| Hydrangea Paniculata Limelight Before Pruning |
After I cut the tall stems, took out others that were crossing and growing inward, and those that were thinner than a pencil, it emerged looking like this:
 |
| Hydrangea Paniculata Limelight After Pruning |
You may not have time for this extensive pruning. Know, however, that pruning makes your plant healthier, stimulates new growth, and will give you stronger stems and better flowers if you do. If you don't prune and don't deadhead, here's what happens:
 |
| Hydrangea Paniculata Not Deadheaded Showing New Season Flower |
Make sure as you move from plant to plant that you disinfect your cutting tools. You don't want to unintentionally move pathogens around your garden. Disinfecting is easy. You can use Lysol® spray on your tools to get into the crevices which can harbor the invisible germs. Studies prove it kills most germs in an average home garden. Your other choice is to make a spray of a 10% solution of rubbing/isopropyl alcohol from your home medicine cabinet using a spray bottle from the dollar store. Don't forget to wipe down your gloves/hands.
You're probably wondering what to do about your other hydrangeas: bigleaf, climbing, oakleaf, and mountain hydrangeas. They all flower on wood that grew last year, i.e., old wood. Unless you want to remove this year's flowers, the short answer is don't touch them. You are in the HYDRANGEA DANGER ZONE™. But it's not that simple.
I'll be posting about what to do with them in the next few weeks. If you can't wait until then, you can go back to my 2018 posts when I wrote about this same topic. It never gets old. OR you can attend one of my 2 upcoming classes on hydrangea pruning:
April 16: UConn Master Gardener Program, Bethel CT
Topic: Pruning Hydrangeas: Let's Do It Right! 1-3 p.m., fee
April 27: New York Botanical Garden, Bronx NY
Topic: Pruning Hydrangeas: What Stays, What Goes, and When 10 am–1 pm, fee
