Arborescens are extremely cold hardy. I would leave it be and enjoy the flowers for however much longer they last. The plant really does not need to be under cover or given protection until the nighttime temperatures routinely drop into the low 30's and it drops leaves and enters dormancy. And that's more the sake of the root mass not freezing....the top growth should be fine.

We are also dropping into the 40's at night now but my hydrangeas in pots stay out all winter. And I don't grow any arborescens :-))

Thanks gardengal, I would plant now but have some rearranging too do come Spring

I might be inclined to heel it in, either planting the pot in a well-drained spot or more likely burying the pot in a pile of loose mulch. I definitely wouldn't put it in the shed until it has lost its leaves if that is how you decide to go.

Yeah, the shrub looks to be in great shape so enjoy it some more. Let Mother Nature drop a few 40-degree hints so it knows it is time for it to go to bed. When it has gone dormant theeeen put it in the shed. I would speed the process only if I knew there was going to be incoming very bad weather (meaning drops to very cold temps like the low teens).

The only thing I do in some years is to put rollers early in the Fall, in case I forget to pay attention to the weather forecasts and there is bad weather suddenly for tonight or something like that.