Magnolia's need to be planted in ericaceous soil (available from garden centres) To avoid damage to your drive I would suggest you keep it potted - the pot (which can be inlarged as the plant grows) can be 'planted' below the soil level which will help to keep the roots cool in the hot weather, a layer of gravel on the top will also help retain water - each winter you should lift the plant, trim the roots to avoid the tree becoming root bound and infill with fresh soil (rather like bonsai) - Good luck!