Magnolias don't make great pot subjects - they hate root disturbance, and you have to pot up as the plant gets bigger, shouldn't put a plant that's in, say, a 5 litre pot when you get it straight into 130 litre pot.

thanks much appreciated,back to drawing board

There are a few dwarf varieties of M. grandiflora that make fairly good pot subjects, the most widely available of which is 'Little Gem'. Although as Bamboo says, you shouldn't plant straight into a 130 litre pot, (which is liable to cause root rot, amongst other things) but work your way up in sizes.

There was a magnolia grandiflora in the grounds of an hotel I worked in and it grew to about 4 metres and that was after some idiot decided to prune it back. It took about 4 or 5 years to flower again. I think it might be a bit large for a pot of any size.