By Wagger
Buckinghamshire,
United Kingdom 
Callistemon.
I've read that Callistemon Rigidus is the hardiest for the British climate and that it is only hardy to -5degrees. Now there is something niggling at the back of my mind about something I read or heard years ago that somebody had discovered callistemon could withstand far more cold than was thought so long as they were growing in wet ground. This seems to go against all advice. Am I going mad or do I really remember this? Help to save my sanity please, lol.
24 Jul, 2010
I haven't heard that before, though I know that Callistemon likes moist conditions, but well drained soil (now there's a contradiction in terms). I've got Callistemon citrinus 'Splendens' in a pot on a sheltered, south facing balcony - I think whether it survives or not is dependent on the micro climate surrounding the plant - a sheltered, sunny spot out of east and northerly winds makes them more likely to survive.
24 Jul, 2010