Depends on the size of your container :-) Pretty much any hydrangea can be grown in half whisky barrel. Otherwise, any dwarf or compact growing variety would work - 'Pia', any of the Cityline series, 'Pee Wee' oakleaf, 'Little Honey' oakleaf, 'Little Lime' or 'Little Lamb' paniculata. For any of them morning sun and afternoon sun is best, although the paniculatas can tolerate a fair amount of sun if kept well watered.

Thanks Gardengal,
I don't have a container yet. I'd buy one the same time as my hydrangea. Oh yes, the Cityline series. I forgot about them. I have Little Lime in my garden and I just love it. Great idea. Thanks again for your help.

There is a new paniculata 'Bobo'. Supposed to be very compact and to bloom prolifically. It got a gold Floral Award in Europe.

I bought 3 of them this spring and quite excited about them.

I just bought 2 Cityline Rio plants this year and am starting them out in containers. I can't wait to see them bloom!