Hello, ashAley. I would pay attention to the two sections titled Cold and Fertilizers (below) to see if any of them applies.

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. If you want to check, you can always do a scratch test 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. But Dr. Dirr points out that oakleaf hydrangeas have a remarkable ability to bloom in full shade. Raising the canopy of trees that provide shade for example may help change a cold micro-climate. Trees that also have shallow roots will compete with all hydrangeas for water and fertilizer as hydrangeas usually have roots in the top 4".

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.

Thank you! You’ve given me a lot to consider. Would coffee grounds help now? Our average last frost date is May 3rd according to farmers almanac,

Move south? Just kidding. Mine are almost in full bloom here in the Atlanta area.

Snow Queen

Snowflake

Ellen Huff

Harmony seems to be the slowest to open

Little Honey is a bit later than the others as well. I had the major limb die on me this year but it is still spreading.

Bummer! That’s what I was thinking.. will have to think about relocating it.

I have 2 oak leafs I planted from 1 gal plants 2 years ago. They are now waist high. Planted on East side of house, zone 7. I took these pics today. Panicles

are 10-12” long. They’re magnificent. I’ve never fertilized. I expect yours is not receiving enough sunlight.

I don’t know why the pictures insist on being sideways when I post them 😫

Jackie, on your photos being sideways - I assume these were with your phone? If so, there is a gyroscope in today's modern phones for orientation. While it may appear correct on your phone, it can be disoriented when posted to a website that does not look at the orientation flag embedded in each picture. Even the newer cameras use the same technology. The best way to get around this issue is to download your photos to a computer, reorient them there, resize for posting on line especially on GW due to glitches that often will fail based on file size.

I will get photos from folks in my email that will be sideways and even upside down at times. It can be irritating for the viewers but we hope that one day that the software will look at the orientation flag and fix it when it is uploaded.

One more note about this issue. If you shoot straight up or down in landscape mode, the gyroscope will fail and the photos will often come out "sideways". That is all in the physics and geometry of the gyroscope sensor.

BTW, where do you live? The hydrangeas you posted are very nice!

Here are some oakleaf hydrangeas at a church I took a few years ago. The church had them pruned back by at least half after the flowers browned so the blooms the next year were not as glorious.

May 21, 2011

showing no ill effects from years before heavy pruning (this was April 29, 2017)

Thanks for the info! I’m in zone 7. In looking at your photos, which are lovely, I wonder if I made a mistake putting my bushes as close to the house as I did? Hope they don’t damage my foundation since it looks like they get quite large, although I don’t know what the root system is like.

Jackie,

I don't think oakleaf hydrangeas will hurt your foundation at all. They may be in the way for maintenance at which time you can tie them up and out of the way or cut them back. We had to cut our azaleas hard at our last house when it got around to painting the house.

We cut these Coral Bell Azaleas (5 of them) back hard (maybe 12 to 18 inches from the ground) at least 3 times in 22 years just to paint.