Magnolias do not like root disturbance. If it absolutely has to be moved, it should be done in early spring, getting as large a rootball as possible

i moved mine 5 years ago,my daughters bought it for me and i keep it in a pot for the first year,that was fine,then thought id move it......4years down the line and no flowers,maybe this wasn't such a good idea,having said that,it looks like this might be the year for flowering,so if you are moving yours,i wish you well, but like Andrewr say's,take as much soil around it as possible, so it dosen't notice the move will help.

Thanks for the advice both - It has been insitu for a good few years and has flowered well which is why I really don't want to lose it but I am having to reorganise my front garden so a move is essential. I was thinking about keeping it in a potato sack until I can relocate it in its new space?