Ask a Question forum→Oak leaf hydrangea not blooming!

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Ann Arbor, MI
ashaley
May 21, 2020 11:33 PM CST
I moved into my place almost 3 years ago and I inherited a small oak leaf hydrangea. It hasn't bloomed since I got here. The first year, I didn't really know what it was and I moved in toward the end of summer, so I didn't touch it. The second year, I knew what it was, and left it alone to see if it would bloom, but it didn't. This year I read up on it a bit, but it appears that it's not going to bloom again.. maybe I'm too early or pessimistic but I want it to bloom!

Some considerations about the plant and placement:

1. The leaves look healthy and green as far as I can tell. I attached a couple pictures. It appears a bit woody, so I did prune off any woody branch that did not have green growing from it last week.

2. It is planted on the south side of my place in a mulched garden bed. There is a large maple tree that is also here and unfortunately it's root system is very shallow and is taking over the garden bed 😩

3. I live in Ann Arbor, Michigan.

It also gets quite a bit of shade, but I've read that doesn't matter as much for this type hydrangea.

I know that hydrangeas like acid, so I was planning on buying some Miracle-Gro® Water Soluble Miracid® Acid-Loving Plant Food.

Does anyone have any more suggestions or tips for me? Id rather not relocate it if I don't have to...

Thanks!



Thumb of 2020-05-22/visitor/60d001
Thumb of 2020-05-22/visitor/c9cc3c

[Last edited by ashaley - May 22, 2020 3:37 AM (+)]
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Name: one-eye-luke US.Vet.
Texas (Zone 8a)
Quitter's never Win
Hummingbirder Birds Organic Gardener Dog Lover Cat Lover
oneeyeluke
May 22, 2020 2:33 AM CST
For blue flowers you need a pH of (pH 5.5 and lower) and for pink flowers you need a pH of (pH 6.5 and higher). I don't know anything about Water Soluble Miracid and I'm a little skeptical of it. When I planted Oak leaf hydrangeas, I had to acidify the soil with a peat moss and shredded pine bark mixed with the soil.

If you sent a soil sample to the soil lab you could find out what you have before you pour something on the ground, that you don't know about.
NOT A EXPERT! Just a grow worm! I never met a plant I didn’t love.✌
Ann Arbor, MI
ashaley
May 22, 2020 3:34 AM CST
Thank you for your insight! I see what you're saying about the soil test.. I have also heard that oak leaf hydrangeas don't turn blue or pink, usually only cream or white only. Am I right in this?
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
May 22, 2020 4:28 AM CST
Hello, ashaley. I would pay attention to the two sections titled Cold and Fertilizers (below) to see if any of them applies. I would correct oneeyeluke's first statement above though. Oakleaf hydrangeas do not have blue or pink flowers whose color can be controlled by acidifying; the blooms are always white, may turn a little pinkish and then they turn brown. He and I then agree that oakleaf hydrangeas only need acidifying to prevent leaf chlorosis in places where the soil is alkaline or when growing a hydrangea in pots.

Cold - Oakleaf hydrangeas are hardy to Zone 5 but its bloom hardiness may go south before reaching that zone. A colder micro-climate in this location may make things more difficult for the flower buds. If this planting location makes things colder, transplanting may be useful. The flower buds are invisible, develop in late Summer to early Fall and then open in the Spring. They are located around the ends of the stems.

Timing - are other oakleaf hydrangeas near you now blooming or not yet? I would take a cue from nearby ones. I would also look in what kind of setting they are (sunlight-wise, etc).

Pruning - I would not do any pruning until after the end of May or the start of June. The ends of the stems is where flower buds reside so pruning may cut them off. Wait until then to see if they leaf out late and then bloom. If you want to check, you can always do a scratch test -but very carefully- against the bark to see if you see "green".

Fertilizers - Too much of a high nitrogen fertilizer can be a problem as it tends to keep the plants growing nice, lush green leaves with few or no blooms. Your chosen fertilizer is one example of that; it has 30% nitrogen (its NPK Ratio is 30-10-10). As large amounts of nitrogen accumulate, you get no blooms. Grass fertilizer pellets that get to the hydrangea would have the same effect as they too are high in nitrogen.

I would use either (a) no fertilizers, (b) a slow release, general purpose chemical fertilizer with a NPK Ratio around 10-10-10 or (c) about 1 cup of cottonseed meal, organic compost or composted manure applied only once in Spring, around two weeks after your average date of last frost. That is it for the whole year. That would be good enough for the whoooooole growing season as these plants are not heavy feeders like roses.

Late frosts - If the plant breaks dormancy before your average date of last frost (2nd-3rd weeks in May), the sap may start flowing just as late frosts arrive and kill your flower buds. So try using frost cloth, watering deeply before the late frost and maintaining lots of mulch under the shrub.

Early frosts - To minimize damage from early frosts, I would make sure never to fertilize them in the Fall. A better bet may be to not fertilize them at all and let them feed off the decomposing mulch. If this had been a new plant, I would fertilize it only until it became established. So try using frost cloth, watering deeply before the early frosts and maintaining lots of mulch 2-4" under the shrub.

Stop all forms of fertilizing about 3 months before you average date of first frost (2nd week in October for you). That includes coffee grounds. This will minimize damage from early frosts because if you fertilize, say, in September and then get a first frost in October, the plant may be in "grow mode" and the flower buds may get zapped.

Dry times - after the plant goes dormant and the leaves brown out, do not stop watering completely. Reduce waterings to once a week or once every two weeks depending on the amount of rainfall. Do stop when it rains a lot, when temperatures go down to freezing and the soil freezes. Resume when the soil has thawed and you see leaf out.

Sunlight - Dense shade can reduce the number of blooms and can sometimes detract from producing their famous fall foliage. Raising the canopy of trees that provide shade for example may help change a cold micro-climate. However, I should point that Dr. Dirr, a hydrangea guru, says that oakleaf hydrangeas tend to bloom in more dense shades than the other hydrangeas.

Finally, it is possible that the previous owner of the house knew about this problem but was only interested in the plant's fall foliage so the owner took no action to replace the plant or actions to help produce blooms.
[Last edited by luis_pr - Jun 1, 2020 4:11 AM (+)]
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Ann Arbor, MI
ashaley
Jun 1, 2020 1:45 AM CST
Thank you Luis! That was very helpful!!!

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