As the blooms age, they will change colors. The exact color sequence of a given variety depends on the type of hydrangea and on the variety. The color of oakleaf blooms is also affected by nutrients (not by soil Ph though), environmental conditions present when the flower buds open, etc. Ruby Slippers, for example, can turn from white to shades of pink, to shades of green and add some burgundy splotches before turning brown. RS can also skip colors if temperatures are too hot and-or its root system is still quite small and gets heat stressed. Here in Texas, shades of pink may either not occur at all or they may occur for short periods as the sepals are not bred to thrive in our dry, low humidity and extremely excessive temperatures past 100° daily from June through September. So even though you can have short duration spikes to 100°F, it is not daily for 3-4 months and thus, you may be able to achieve longer lasting periods of shades of pink than I do here. Which variety do you have? Maintain the plants always mulched (3-4" past the drip line) through the year and always keep the soil as evenly moist every day during your dry summer season. Not dry and not wet either. Water the soil deeply if a finger inserted into the soil at a depth of 4-6" in several spots feels dry; skip watering if it feels wet/soggy. Never water the leaves to avoid fungal and bacterial leaf/bloom diseases. Use drip irrigation or soaker hoses. If a sprinkler is all you have, water the soil deeply from 6-8am so the leaves do not remain wet for long periods of time. Oakleaf hydrangeas are very drought tolerant but do not let the soil remain wet/soggy for long periods of time as they can quickly develop root rot.

Might be better to go with an arboresecens hydrangea such as Hayes Starburst (my current favourite). An oak leaf such as 'Gatsby Moon' will change bloom colour...but not to pink. Will shade to pale green. I am not terribly keen on that particular hydrangea pinkiness but find soft greenish colourings to be as serene and restful as the plain whites.

HS is a low growing, compact arborescens. The flowers may be heavy when wet and the stms may tend to flop so consider getting tomato cages, stakes, etc. if you get a HS. Arborescens cultivars may also be heat sensitive during the summer.

I actually like oakleaf hydrangea blooms changing to pink then a burgundy color. I had one in my old house and it was stunning in the fall with deep wine red leaves. Then one day it suddenly died. Never figured out why, maybe we had a wet spring? I just got 2 plants from a friend and will plant them in a raised bed. Hopefully they will survive

The flowers on my Little Honey have never turn pink. They remain white until late season when they finally fade to a tan color. But it is not a heavy bloomer in my garden.

Alice stays pretty white before drying to tan

They all change to some degree, even the H. aborescens -- most of them go through a greenish stage before they dry to tan. I've never had an oakleaf that doesn't turn at least a bit pink, but I would think some get pinker than others, and I don't remember the cultivars I've had.

Oakleafs heee in Texas rarely get shades of pink. RUby Slippers is the one does in sone years but not always

"Oakleafs heee in Texas rarely get shades of pink."

I wonder if any of that has to do at least in part to the cooler temps we get and the more northerly latitude up here farther north than you. IDK. Just wondering.

Ok, this is weird. My last comment looks different than it used to. It also says it was edited 4 hours ago but I was busy cooking, eating and watching TV then! Do you guys think my Id/password got hacked???

" I wonder if any of that has to do at least in part to the cooler temps we get and the more northerly latitude up here farther north than you. "

I wouldn't think so. Here in the Puget Sound area of the PNW, we are likely further north and definitely cooler in summer than even MI and with the exception of 'Ruby Slippers', I can't think of a cultivar of oakleaf that will routinely turn pink in late season. At least, nothing like 95% of the paniculatas. The white flowers almost always fade to a tan color as they age.

Very nice bloom. Reminds me of Amethyst: https://www.heritageseedlings.com/page_388_40/hydrangea-quercifolia-amethyst

z8b Oregon: I have Munchkin in an extremely hot and sunny position, and it turns pink for about 20 minutes! I just ordered Gatsby Moon specifically because it supposedly goes from white to green with no pink period, but also for the dense, luxurious, panicles. But really, for me H. quercifolia is all about the late, long lasting autumn foliage color.

" But really, for me H. quercifolia is all about the late, long lasting autumn foliage color. "

Oh yes!! My 'Little Honey' only produced 3 blossoms but it is still sporting gorgeous autumnal colors on its foliage in mid December! And will typically hold that old but colorful foliage until it is pushed off in spring by the new growth.