There are suggestions for winter protection here:
http://www.hydrangeashydrangea...
Regarding the fertilizer, it's not just the analysis but also the amount. A little bit of high N won't have the same impact as a large amount with the same analysis. Having said that, since the flowers are formed on the previous year's wood the buds are already there (or not) by spring so fertilizing then wouldn't make any difference I'd have thought. I actually don't fertilize hydrangeas at all but I can't grow the macrophyllas because it is too cold here and don't know what their demands might be.
