Ask a Question forum→Hydrangea Old wood pruning

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Andover, MN
jordan572
May 31, 2020 12:20 PM CST
Hi I am just having some issues on deciding if I should prune the old wood off my hydrangeas. I live just 30 minutes north of Minneapolis Minnesota and have a variety of endless summer original and endless summer, summer crush hydrangeas that were planted last year during summer. They were container size #5.

This year I have substantial new growth on all of them, however each has about at least a dozen old wood stocks that have black buds on them and appear to be dead. I left them be but now at the last day of May they look terrible and are showing no signs of budding. So this morning I decided to start cutting the old wood off due to no active budding on these stocks. When I cut this what I think is dead wood off at the base the inside of the stocks are green. Am I being impatient? They just look terrible the way they sit, I have about 20 of them all looking identical except on 1 hydrangea, 2 branches are showing life on the old wood. What are your thoughts?
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
May 31, 2020 1:54 PM CST
Welcome to NGA, jordan572. It would help to see what you are seeing to make sure I understood about black buds.

I am guessing you are referring to leaf buds that dried out during winter although if you winter protected, your plant could have developed flower buds that recently opened and then got zapped by a late frost so they now look black or dark brown. May 8-9 were the coldest recent dates in May with temps below freezing, something that can zap leaves, flower buds, stems or any mix of them.

If the dead stems do not leaf out by the end of May or so, the chances of leafing out fall fast. But that is a generality for the most of the U.S.; closer to the border with Canada, some people may wait until June. In Andover, MN, I would wait.

When not sure if you want to remove the old wood, you can very carefully do a scratch test against the sides of the stems to see if you can see "green" or you can start pruning from the top in 1 or 2" increments (stop when you see "green" or get to the bottom.

Sometimes, you can see that they will not come back because the center of the stem looks hollow. Other times, you see green but they still do not leaf out and "officially" brown out later in June.

Winter protection will help preserve the stems but it has to be applied early in the Fall, after the plant goes dormant and the leaves turn brown. Then remove it around two weeks after your average date of last frost plus two weeks (the average is the end of the first week in June for you):

https://www.plantmaps.com/inte...

Since the plants lost many of the stems, I would not expect blooms in early Spring. Because they are remontant, I would expect that the new growth that is currently coming out of the base will produce blooms if it gets tall enough and old enough by mid to late Summer. That is how the rebloomers are supposed to work in cold zones like yours.

The one hydrangea whose stems are leafing out may produce blooms or not. Hard to say as hydrangea flower buds are usually hidden inside the stems. But, I hope they do bloom. There is going to be a catch 22, when this happens to me, the plant looks aesthetically weird because that one or two stems are very long compared to the new stems and I end up pruning the stem after it blooms to get all the stems growing at about the same length.
Name: Paula Benyei
NYC suburbs (Zone 6b)
Image
Turbosaurus
May 31, 2020 4:22 PM CST
They're tough guys, so you certainly didn't do any permanent damage by cutting them, although you significantly reduced the number of flowers you'll get this summer

Hydrangea produce new buds for next spring at the same time they are producing summer flowers. 99% of the time The buds survive the winter, but often the outside most leaves are damaged by frost, especially when they start to open in the spring and let in cold air of late cold snaps. The buds are almost always black on the outside come spring.

If you cut them, even in spring, they will still grow, but You're removing a ton of potential blooms. to get the best blooms you should leave the buds till you have consistent 50-60 degree temps before you decide if they're viable or not. Almost every stem on my hydrangea, if you look close, the lowest leaves have some curling or damage, but they also have flower buds at the tip.

Try to be patient. They should flesh out quickly to cover any flaws. If you already cut, They'll grow back, although those new stems won't bloom till next year

The plural of anecdote is not data.
[Last edited by Turbosaurus - May 31, 2020 4:25 PM (+)]
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Andover, MN
jordan572
May 31, 2020 7:29 PM CST
luis_pr said:Welcome to NGA, jordan572. It would help to see what you are seeing to make sure I understood about black buds.

I am guessing you are referring to leaf buds that dried out during winter although if you winter protected, your plant could have developed flower buds that recently opened and then got zapped by a late frost so they now look black or dark brown. May 8-9 were the coldest recent dates in May with temps below freezing, something that can zap leaves, flower buds, stems or any mix of them.

If the dead stems do not leaf out by the end of May or so, the chances of leafing out fall fast. But that is a generality for the most of the U.S.; closer to the border with Canada, some people may wait until June. In Andover, MN, I would wait.

When not sure if you want to remove the old wood, you can very carefully do a scratch test against the sides of the stems to see if you can see "green" or you can start pruning from the top in 1 or 2" increments (stop when you see "green" or get to the bottom.

Sometimes, you can see that they will not come back because the center of the stem looks hollow. Other times, you see green but they still do not leaf out and "officially" brown out later in June.

Winter protection will help preserve the stems but it has to be applied early in the Fall, after the plant goes dormant and the leaves turn brown. Then remove it around two weeks after your average date of last frost plus two weeks (the average is the end of the first week in June for you):

Since the plants lost many of the stems, I would not expect blooms in early Spring. Because they are remontant, I would expect that the new growth that is currently coming out of the base will produce blooms if it gets tall enough and old enough by mid to late Summer. That is how the rebloomers are supposed to work in cold zones like yours.

The one hydrangea whose stems are leafing out may produce blooms or not. Hard to say as hydrangea flower buds are usually hidden inside the stems. But, I hope they do bloom. There is going to be a catch 22, when this happens to me, the plant looks aesthetically weird because that one or two stems are very long compared to the new stems and I end up pruning the stem after it blooms to get all the stems growing at about the same length.



Thumb of 2020-06-01/jordan572/3369ac
Thumb of 2020-06-01/jordan572/7c54f0


Thank you for the detailed response, from what I am witnessing I will consider your replies and comments to these attached pictures as well. I only pruned about 4-6 of them so the other 8-10 I will leave and see what the next week or so brings. We are getting real warm this week so perhaps I will see some change. I totally understand the visual dissatisfaction you see when a few long stems are budding on old growth while the new growth is short and still filling in. If that is the case I will trim much like you have had to. Again thank you for the thorough response I appreciate that.

On one of those pictures you can see a few buds coming off the old wood on the right hand side, so far none of the other plants are showing anything promising. Is it right to assume though that a green stalk when cut is still alive although on the outside it is completely dead looking?
Andover, MN
jordan572
May 31, 2020 7:32 PM CST
Turbosaurus said:They're tough guys, so you certainly didn't do any permanent damage by cutting them, although you significantly reduced the number of flowers you'll get this summer

Hydrangea produce new buds for next spring at the same time they are producing summer flowers. 99% of the time The buds survive the winter, but often the outside most leaves are damaged by frost, especially when they start to open in the spring and let in cold air of late cold snaps. The buds are almost always black on the outside come spring.

If you cut them, even in spring, they will still grow, but You're removing a ton of potential blooms. to get the best blooms you should leave the buds till you have consistent 50-60 degree temps before you decide if they're viable or not. Almost every stem on my hydrangea, if you look close, the lowest leaves have some curling or damage, but they also have flower buds at the tip.

Try to be patient. They should flesh out quickly to cover any flaws. If you already cut, They'll grow back, although those new stems won't bloom till next year



I appreciate the reply, for now I will listen to the advice on the forum here and give it a bit more time before I prune away the old wood. I have pruned some but not most, so it will be a good comparison come the end of the year to see how they fared. When do you think would be a reasonable time to give up on the old wood and prune considering the region I am in? This week is mid 80s which is very warm for us this time of year. Thank you again for taking the time to help me out.
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
May 31, 2020 7:41 PM CST
Yes, the older parts of the stems are more woody. This year' s growth will be green. Last year's growth may be green or woody looking.
Name: Paula Benyei
NYC suburbs (Zone 6b)
Image
Turbosaurus
May 31, 2020 8:02 PM CST
I think you did the right thing.

Those buds are fried. I would cut the woody stems off low because even if the heart wood is green, they won't bloom this year, and new growth will be heartier if it has less damaged stem to traverse. You were right to cut them this year
The plural of anecdote is not data.
Andover, MN
jordan572
Jun 2, 2020 6:13 AM CST
Thank you all for the help, I will likely prune the remaining dead stocks on the rest of my hydrangeas. I also purchased some high phosphorus fertilizer in hopes to aid in flowering later this year. How much of that do you like to apply?
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
Jun 2, 2020 6:44 AM CST
I add none to the hydrangeas but some to the roses. ☺ Hydrangeas are not heavy eaters like roses are and do not benefit from extra ferts most of the time. As the new stems from this Spring get taller and older, they will take the task of developing flower buds and opening them... by around mid to late Summer or in the Fall.

Once the plants are established and assuming no soil nutrient problems, suspend the ferts and let them feed off the decomposing mulch.

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