Oak leaf hydrangea not blooming!

[ash-a-ley]

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 a little too early, or pessimistic, but I want to see some blooms!!

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 (taken at night, sorry.) 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 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!

[TNCatHerder]

It may not be getting enough sun with that big tree next to it. The tree may also be robbing the soil of all of the nutrients the flower needs. If that's the case I don't know if fertilizing/feeding it will make a difference. I've had Hydrangeas before but the Oak Leaf type is new to me.

[luis_pr]

Hello, ash-a-ley. I was not sure where to leave you a reply so I left one here too.

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. Raising the canopy of trees that provide shade for example may help change a cold micro-climate. Dirr says it has a remarkable ability to flower in dense shade so sunlight is not usually a problem but planting it away from the competition may help... as its roots are shallow (top 4" or so)... specially if the other tree also has shallow roots. I have one Snow Queen specimen planted under a Crape Myrtle, beside a holly and beside a wooden fence (7' away) on the third side. So it is in full shade. And it has always flowered for me so sunlight is not (yet) causing issues.

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.

[Dissily Mordentroge]

I inherited a young Oakleaf Hydrangea 16 or so years ago when I moved south to Tasmania. Temperatures when we first moved descended to -7 but for the last four years only reach -3 with far fewer frosts. (dare I mention global warming?) I only fertilise in early spring with sheep manure. The location receives approx one hour of low on the horizon sun in the early mornings. A mature snake bark maple and a shed overhang the hydrangea.
I’ve had blooms galore every year despite the shade and changing temperatures. The soil is a deep friable loam of neutral PH without any mulch.

I’m curious why coffee grounds might be needed.

[luis_pr]

They are not "needed" but some people like to use them in the garden to provide additional micro-nutrients that some regular fertilizers do not include. Note that, although coffee is acidic, most of the acidity is lost during the preparation of the coffee so the coffee grounds do not have much and should not be used by themselves to acidify the soil.

Composted manure, organic compost and cottonseed meal are all good fertilizers to use.

[Dissily Mordentroge]

Never did pay much attention to the claim used coffee grounds were acid due to the fact none of my acid hating plants ever objected to having it dumped around them.
As to fertiliser I’ll stick with sheep manure as it works for me in my soil and my location. I do notice one advantage it has with other kinds, especially with roses, it breaks down slowly often requiring only a single application per year. Some claim sheep manure varies greatly in value depending upon the time of year it’s collected. In my location I’ve never noticed any difference. Maybe the short summers and long winters here in Tasmania have something to do with it?

[luis_pr]

Just use it (the coffee grounds) to provide additional minor nutrients (especially in potted plants). Similar to other "weak" fertilizer products like liquid seaweed or liquid fish that can sometimes be used during winter times. Continued use of your compost sounds like a good plan. Composted cow manure is what is commonly sold on this side of the pond (Texas). Stay safe!