Hi

Not the easiest shrub to move to be honest ...

How long has it been growing in the same spot and what variety is it.

Best method but does take time (12 months ) but more successful.

Measure out from the trunk about 2 feet 0.6096, and dig out two feet deep and dig a trench out around the shrub (you can do that November or when the leaves have fallen ) , doing this it will cut the main roots once that is done fill with compost and wait till the following autumn (over the year the magnolia will produce new fine roots)

Next Autumn dig out the trench and then undercut (under the bush) with a sharp spade and pull a plastic sheet under its fiddly but take your time once completed.

Tie together the plastic sheeting to create a rootball , move to new area plant at the same depth and then pull out the plastic sheet and make sure you look after all spring and summer dont let it dry out THE 1st year of the move.

Gg