I saw on a site that the Callistemon or bottle brush needs to be pruned late, as they're realy susceptible to the wet, and the late frost. they can have new growth scorched in the winter. just type in Bottle brush pruning into google, there are lots of sites telling you what to do. hope this helps i just prune mine whenever i need to and its fine, it had lots of beautifull flowers this year all my neighbours comented on it.