Hadn't head of this so just looked it up - a bit of a stunner!!
The site I looked at says it grows to 2m so it might struggle in a pot after a while, unless you're able to pot it on every couple of years. Hydrangeas are thirsty plants so you will need to be watering it on days when there's no rain - try adding water retaining crystals/gel to the compost and use a thick layer of mulch.

Thanks very much Urbanite - I suspect I'll wait until the autumn to make up my mind whether to keep it in a large pot or plant it in the ground. Not sure there's room for it in the garden (though it sounds worth making room for!). If I keep the pot, your suggestion of crystals or gel and mulch is very useful.

I like seeing white hydrangeas in pots because they don't get splashed with mud but they are generally happier in the ground.

OK - I'll bear that in mind - thanks.