November probably. Be a good idea to discover why its not happy where it is first though - what's the soil like and what's its general situation? And when you planted it did you notice whether the roots went round and round in the pot - they should be loosened as sometimes they seem unable to do this for themselves and this stops them growing.

Hi, it sounds as though there is something not right about whee soil isn'tre you're growing it, ideal conditions are in moist, well drained, humous rich, preferably acid to neutral soil, in full sun to partial shade, with shelter from strong winds, although M stellata will grow in alkaline soils as long as it's moist, if you have to move it, best time is whilst it's dormant in winter, but make sure that the soil isn't waterlogged or frozen, but Magnolia's don't like being moved, and may sulk for quite a while, Derek.