Please help me understand Hydrangeas

viche(7a MD)July 24, 2006

I've read a few articles about pruning hydrangeas, but I'm still a little confused.

We inherited 4 large hydrangeas when we bought our house. I believe that they are macrophyllas. We had a landscaper help us out this spring, and he pruned back the plants from about 5 feet tall down to roughly 3.5 feet. He said that there was a lot of completely dead stuff and that he just cut out the branches whose buds were completely dead and dried up. The plants started growing new shoots and now are close to 6 feet tall. There are probably about 15 blooms so far.

First of all, I though macrophyllas bloomed on old wood. But all the blooms on this plant are off of the shoots that sprang out of the buds this year. I just don't get the "old wood" idea. I've never seen a hydrangea where blooms burst directly out of the old wood's buds.

Secondly, if I don't want them to grow over 6 feet, how do I prune and when? I've read that I should cut the spend blooms down to the next set op opposing buds, but that would hardly control the size of the plant. Also, there are opposing buds at every set of opposing leaves, about every 6 inches all up and down the new shoots. Can I just cut the new shoots down where they sprouted from the old wood, or will the old wood no longer produce new buds and therefore new shoots and blooms next year.

Please help me understand.

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silvergold(z5a WI)

Hi there. Well, to help you out we really need to know what type of hydrangeas you have. Here is a web page that might help (and it also has some tips on prunning). Come back and let us know what matches best to yours.

Here is a link that might be useful: Hydrangeas

    Bookmark   July 24, 2006 at 5:05PM
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viche(7a MD)

Two of them are definitely mophead macrophyllas, probably Nikko Blue. These are the ones with the new shoots that are up to 6 feet tall. There are about 25 blooms now on these two bushes.

There are two other much smaller bushes (maybe 2-3 feet tall) with white and green striped leaves like a hosta). I haven't seen these flower yet (maybe due to deer eating the tips off or being shaded by the big guys). The stems on these seem to be sprouting from the ground instead of from buds that were on the old wood stalks. Then again, these were smaller to begin with and the landscaper did cut these down to only about 1.5 feet tall in the spring.

    Bookmark   July 24, 2006 at 6:30PM
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viche(7a MD)

Do the descriptions above inspire any suggestions?

    Bookmark   July 25, 2006 at 7:01PM
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silvergold(z5a WI)

Sorry - I would have responded. I don't have a lot of first hand knowledge about macrophylla. (Being a northern gardener I have mostly arborescens and paniculata). Regarding the variegated shrub - are you sure they are hydrangeas? Any way you can take pictures?

    Bookmark   July 25, 2006 at 7:40PM
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lkaa(z7 NOVA)

I think I can help. The old wood means that new growth comes from the previous years branches, not new shoots that are coming up from the base of the plant. In the spring (once they start leafing out) I cut mine back to the third strongest bud from the bottom to keep them in check, but they still get about 5 feet tall (my Nikkos).

The variegated one may be lemon wave. It is grown mostly for the foliage and is a lacecap variety.

A useful site for all kinds of information on pruning and care is http://www.hydrangeasplus.com/home.php. They have a great FAQ section. I haven't had much luck with my purchases from there, but I chose some that may not have been the best choices for my needs.

Here is a link that might be useful: Lemon Wave

    Bookmark   July 26, 2006 at 8:03AM
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leslies(z7 No VA)

viche; I understand your old wood/new wood question, though I don't know the answer. I, too, inherited a group of macrophyllas last spring that bloomed quite well last summer. Only problem was that they bloomed at about 6' and fell over in the first rain.

As soon as the blooming quit last summer (toward late July), I pruned. As you say, the flowers were located on new green stems that arose out of white/gray wood from the prior year. The pruning advice I had at that point indicated that I needed to prune off a third of the old wood, which I took to mean I had to cut off ALL of the green stems and down into the white wood to shorten it. This I duly did. Plants looked a little sad in the hot, dry midsummer weather, but they recovered and put out new leaves after a couple of good rainfalls.

This year, at the end of a mild winter, all of the purplish buds on the remaining old wood looked unpromising, so I waited. Eventually, new stems broke from the old and, in a few places, I trimmed off old wood above the outermost new stem.

This summer? No flowers!

I have no idea how you get a big macrophylla to bloom at less than 6 feet tall.

    Bookmark   July 26, 2006 at 2:26PM
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viche(7a MD)

lkaa, so I guess that means that you are cutting off entire green shoots and cutting into the old wood?

Leslies, I completely understand your confusion. I get the feeling that not many people have derfinitive answers about hydrangeas or this is so simple that we are missing the trees for the woods.

Is spring the best time to prune?

Does cutting off a 3rd of the old wood mean that you should cut a 3rd of all the stalks back down to the ground or just cut ALL of the stalks to 1/3 their current height?

What causes shoots to bloom or (as in your case) not to bloom?

If you prune down into the old wood, will that old wood sprout new stalks next year and yield flowers?

    Bookmark   July 27, 2006 at 6:18PM
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lkaa(z7 NOVA)

Think of the green shoots that are coming off of the grey wood as the "flower stem" though it may not always produce an actual flower. So in essence, yes your are cutting off the green shoots to the old wood. If you look at the structure of the plant in the winter when there are no leaves, that will help you understand it all better.

Spring is the best time to prune for us because if you prune in the fall you are exposing the stems to a possible early frost which will hurt the plant.

I'm not sure about leslies advise to prune 1/3 of the wood, and why in the summer. Typically it means that you take out 1/3 of current growth to the ground to thin out the plant.

Pruning down into the old wood doesn't necessarily "sprout" new stalks. The new stalks are the "buds" that you see on the grey branches in the early spring that turn into "green branches" and should bloom.

But... they don't all always bloom. I can't totally explain why some bloom and some don't but it seems to be a culture thing, i.e. sun exposure, watering, soil, age and health of plant. My bushes always have tons of blooms, but I don't do anything special...just let them be and prune down to the third strongest "bud" on the old branches each spring.

    Bookmark   July 27, 2006 at 8:59PM
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viche(7a MD)

Wow, lkaa, that made a lot of sense. I wasn't sure if the old wood could produce new buds year after year, but apparently, from what you are saying, they can.

So when I prune down to the "third strongest bud on the old branches", I'm assuming that I will be able to see and count each bud from the ground up, and then just cut the old wood off an inch or two above the third bud from the ground? What do you mean by "strongest"

    Bookmark   July 28, 2006 at 9:15AM
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lkaa(z7 NOVA)

Glad to help. I remember how confusing it was when I first started.

Yes, you will be able to see and count each bud. I generally do it when we are done with the frosts in spring and the buds start to leaf out. The strong ones are showing growth that is nice and lush and fat. The weaker ones are those at the very top of the branch. Just cut to right above where the new growth is poking out.

Here are mine from about two weeks ago...

    Bookmark   July 29, 2006 at 1:04PM
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viche(7a MD)

Great picture! Mine aren't nearly so full.

If I want to cut some to bring inside, I've read that I should wait until they begin to have signs of browning. Then, theoretically, I could cut the entire new shoot off to have nice long stems. You don't think this would interfere with bud production or next years blooms do you?

    Bookmark   July 29, 2006 at 3:09PM
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lkaa(z7 NOVA)

You are correct. I do that all the time and have yet to have any problems with blooming.

    Bookmark   July 29, 2006 at 10:42PM
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viche(7a MD)

Found this old thread that I had started and I have a new question.

This year the snow really hurt some of my hydrangea branches. I just checked and I have buds that are starting to leaf out nicely, but some of this leafing old wood is broken (really cracked and bent) at the base from the weight of snow.

I'm assuming I should just cut that old wood off at the base near where it is cracked/leaning instead of trying to repair/stilt it somehow?

If I cut back enough wood to the ground, will the bush realize that it needs to grow new branches from the ground to make up for the ones I removed?

Finally, what do you do about old wood that has no buds? Should I just cut that branch back to the ground, or might a dead looking, but bud-free branch regain buds next year. I'm assuming if it has absolutley no buds this year, then it's spent, and needs to be removed, but please let me know if I am wrong.

Thanks guys and gals!

    Bookmark   March 27, 2010 at 2:31PM
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viche(7a MD)

Strange, just posted the message above, and this thread did not jump up to the top of the forum.

    Bookmark   March 27, 2010 at 2:34PM
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