I have had no hardiness problems at all with H. quercifolia in zone 6 including 'Snowflake'. Late summer/fall is a great time to plant shrubs and they're usually on sale. Go for it.

Sue

I had a problem with quersifolia planted in a fall once, though it was my own fault because I chose the wrong place for it.
While I found the place where it will be in a part-shade during a summer, I forgot about winter sun and plant become fully exposed to winter sun and winds.
No wonder, all top growth become dessicated and dead by the spring, though roots were well alive and produced a lot of new growth from the base, so it was not a complete loss, just loss of time.
Mulch root zone well and be prepared for partial dieback in a first winter, which is not uncommon for the quersifolias.

Yea! Thank you. I really, really didn't want to wait til Spring. Now the question is...shall I drive to Avant Gardens for them this weekend? Or should I use them as an excuse to go to Broken Arrow Nursery and then I could see 'Amethyst' too....... Disregarding the rain, of course....
ML

Maybe I have it sited poorly but 'Amethyst' has been my weakest growing H. quercifolia. Broken Arrow is a good idea though. Maybe I'll take a ride there myself.

Sue

I planted an H. quercifolia last spring and it was very healthy and did great over the summer. But in the spring, I discovered it had died back almost to the ground. It came back fine, but had to start all over again and didn't bloom this year. So this fall I am planning on mulching it well.

:-)

Quersifolias are notorius to have a dieback in a first winter, no matter when you plant them, spring or fall.
If practical wraping in burlap to protect from wind and winter sun helps greatly.
Regarding flowering, they may not bloom for two years after planting even if you bought them in flowers.

Thanks for that information. :-) I was unaware of it. I don't know why I had it in my head that the quercifolias were hardier and sturdier than the other hydrangeas. The Endless Summer I bought last year, turned out to be much sturdier and made it through with no protection at all and bloomed fine this year.

I have never used burlap to wrap a plant. Do you have to put stakes around the plant and staple the burlap to it? I would really like to be sure it will bloom next year. [g]

Thanks very much ego45. Glad you asked about this mayalena, I didn't think to ask. :-)

" I had it in my head that the quercifolias were hardier and sturdier than the other hydrangeas. "

That is correct, they are sturdier and hardier and don't need any protection in z6 as well as in a most of z5 gardens in order to bloom, though in especially harsh winters flower buds might be ocassionaly killed.
My comments from above were related only to the FIRST winter after planting, after that it wouldn't/shouldn't need any winter protection beside the point that due to their size it simply could be impractical.
In a first two years after the planting they MAY not bloom irregardless of weather conditions, they simply settling in and working on a roots development (re-development if you bought a larger B&B plant).
This is exactly the same phenomenum you may see in Rhododendrons when they completely refuse to bloom or bloom just sparsly in a first two years after planting.

Thanks ego for that clarification. Well then, I will keep my fingers crossed that next year, I might see a bloom or two.

:-)