Hydrangea Annabelle

Biljana

I bought a young plant late summer and planted it early autumn. It looks like this now: the leave are going brown and falling off, but there is a bud on top forming at the same time.  Do I leave it as it is or prune it? Does it look happy or is it dying? Thank you

Palustris

Normal for November. Pruning is done in February/March. It flowers on new wood, unlike H.macropetala which flowers on wood produced the previous season. No pruning is really needed until the shrub gets bigger. However, if the flower stalks droop under the weight of the blooms then you may want to prune, again early in the year.

Loxley

The harder you prune, the bigger the flower heads - the bigger the flower heads, the more liable they are to flop. Although they look beautiful.

amancalledgeorge

And nowadays you can buy the more recent introduction, Strong Annabelle that doesn't tend to flop about as much.

Fairygirl

It's just shutting down for autumn, so all normal. That emerging bud will just gradually die off as it won't have the right conditions to open now.
It can just be left in place over winter @Biljana, until the right time for pruning as already indicated.