All things Hydrangea - Ask Extension
I have a variety of hydrangea plants and am never sure when it is most appropriate to prune them. I would like for them to all be a bit more uniform....
Knowledgebase
All things Hydrangea #879256
Asked July 29, 2024, 1:55 PM EDT
I have a variety of hydrangea plants and am never sure when it is most appropriate to prune them. I would like for them to all be a bit more uniform. I am also experiencing either disease or a pest problem. Do you have any suggestions?
Baltimore County Maryland
Expert Response
Hi Lori. Let me start by referring you to this site from Maryland Extension, which provides a weath of information about the care of hyrangaes, https://extension.umd.edu/resource/hydrangea-identify-and-manage-problems/
I can't tell for sure from your photos, but I think you have Bigleaf hydrangea, hydrangea macrophylla. Generally, as discussed in the Extension article, these bloom on old wood, so the time to prune them is just after the current year's flowers fade, which from your photos I assume just happened. If so, prune them to the desired size now. (This article has a lot more detailed info on pruning hydranageas, https://extension.umd.edu/resource/pruning-hydrangeas/)
At the risk of complicating things, let me note that this pruning rule is not absolute, as growers continually come up with new cultivars and some may flower on new wood. So I suggest doing the pruning now, and see what happens. If next year's flowering is not good as it was this year, then try pruning in late winter/very early spring rather than in mid-summer.
As to the problems you are having, they likely are cause by leaf spot and/or scorching. Scorching is especially likely given the very hot summer we've been having, and in particular could adversely affect the plant in the container. Be sure to keep all your hydranageas adequately watered, as the Extension article suggests. If the potted plant is in full sun, I suggest moving it to a shadier location. There is not much you can do to treat leaf spot, but usually it does not cause long-term harm to the plants. To enhance the appearance of your plants, you could clip off browned out leaves and flowers. To avoid the risk of spreading fungal spores, add water at the base of the plants rather than using an overhead sprinkler. For the same reason, if any leaves fall to the ground this autumn, rake them up and discard them.
Bob
.
I can't tell for sure from your photos, but I think you have Bigleaf hydrangea, hydrangea macrophylla. Generally, as discussed in the Extension article, these bloom on old wood, so the time to prune them is just after the current year's flowers fade, which from your photos I assume just happened. If so, prune them to the desired size now. (This article has a lot more detailed info on pruning hydranageas, https://extension.umd.edu/resource/pruning-hydrangeas/)
At the risk of complicating things, let me note that this pruning rule is not absolute, as growers continually come up with new cultivars and some may flower on new wood. So I suggest doing the pruning now, and see what happens. If next year's flowering is not good as it was this year, then try pruning in late winter/very early spring rather than in mid-summer.
As to the problems you are having, they likely are cause by leaf spot and/or scorching. Scorching is especially likely given the very hot summer we've been having, and in particular could adversely affect the plant in the container. Be sure to keep all your hydranageas adequately watered, as the Extension article suggests. If the potted plant is in full sun, I suggest moving it to a shadier location. There is not much you can do to treat leaf spot, but usually it does not cause long-term harm to the plants. To enhance the appearance of your plants, you could clip off browned out leaves and flowers. To avoid the risk of spreading fungal spores, add water at the base of the plants rather than using an overhead sprinkler. For the same reason, if any leaves fall to the ground this autumn, rake them up and discard them.
Bob
.
Great, thank you so much!
Lori
