Pruning Hydrangea By Types – How Do I Know What I Have?

As you know, we moved into this home a little over two years ago. There was a lot of existing trees, bushes and shrubs that I needed to identify and I have mostly done that. Some of them are still a mystery. But it is the hydrangea bushes, three of them, that are just giving me fits! I don’t know how to prune them! I know that your pruning of hydrangea is based on the type of hydrangea, but how do I know what I have?

Let me describe these bushes. They are located next to my garden shed in part shade and it seems that there are three bases, so I am assuming three bushes are there. I have never found a “tag” of any kind like I have found in other shrubbery at this home, but perhaps I have not dug deep enough?

The blooms on these hydrangea are not super large but they are fairly large snowballs like I would expect a hydrangea to have. Woven in together among these mophead blooms are also some lacecap blooms. That is why I think there are at least two separate types or varieties of hydrangea there. ( There are three bushes there.)

Can color identify which variety of hydrangea so that I can do a proper pruning?  I am not sure. These bloom are white color and gradually fade to a pale green before they turn tan for the winter.  They have never been blue or pink and since we have moved here, I have never treated them with any color soil enhancer.

Do all hydrangea make a color change based on soil pH? I am not sure. My information is that an hydrangea can be treated with aluminum sulfate to cause it to bloom blue, or if you’d want a pink color, I can treat the soil around it with hydrated lime. 

When Should I Prune My Hydrangea?

When we moved here, I didn’t trim those bushes in fall of 2018 or 2019. But they all bloomed very well.  So they are blooming on Old Wood and/or the New Wood which sprouts from the soil around the base. Last summer, I had many branching flower spikes with a bloom at each branched point. 

Why would I think this one is Macrophylla?  Since it blooms on old wood (since I have never pruned) and I have a lot of blooms.  However the leaf does not seem to fit the description of  “short leaf stems” or petioles that are a characteristic of the Macrophylla type.

Could it be Arborescens since those are supposed to have longer older petioles or leaf stems greater than 1 inch and held away from the main stem?

Let me say here that the other varieties of hydrangea that I have completely ruled out:

  • Climbing Hydrangea (Petiolaris) – obviously not a climber
  • Oakleaf Hydrangea (Quercifolia) – not an oak-shaped leaf
  • Panicle Hydrangea (Paniculata) – not a cone-shaped bloom

My Guess on My Type of Hydrangea and How I am Pruning

Based on this research I have done to figure out my type of hydrangea, I am going with this year’s guess as the Hydrangea Arborescens or Smooth Leaf Hydrangea, sometimes just called Annabelle, although the Annabelle is really just a cultivar of this type.

Bloom color – white fading to greenish

Bloom time – June til September

Petiole length – older leaves have > 1 inch petioles

Leaves are heart-shaped,  somewhat thin, and floppy

 

Pruning Hydrangea Arborescens

I have chosen this variety as the identity to my Hydrangea and I hope I am right. I have pruned these here in spring as I will show you in my video. They are supposed to bloom on New Wood so if I am not correct, I may lose all blooms this year. Check out the video.

If I am not correct, I will nurture these bushes and feed them well this year in hopes of getting blooms on Old Wood next year. Since I did have some issues with a possible fungal problem last year, as you see in the video, I will treat them and let them rest. If they are Macrophylla, then they will be all ready to bloom next year, right. At least I may finally find out what they are!

 

Reference links: https://www.gardenfundamentals.com/hydrangea-identification/

                               https://plantaddicts.com/types-of-hydrangeas/

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