Deciduous and evergreen magnolias require very different treatment when it comes to pruning, the evergreens are easy, especially cultivars such as 'little gem', 'kay parris' and 'teddy bear'. They can easily be pruned back to size and shape using basic pruning techniques.
Pruning different Magnolia varieties
Pruning Evergreen Magnolias
The larger growing older evergreen grandiflora magnolias are a little more tricky but can be cut back, you will probably ruin the shape, but it can be done.
Smaller growing types such as MagnoliaLittle Gem, Kay Parris and Teddy Bear, can be either litghly pruned each year to maintain a busy shade, or they can be hard pruned every 5 - 6 years to maintain a bushy shape.
Pruning Deciduous Magnolias
Deciduous magnolias actually require very little pruning and it really is best not to prune the deciduous varieties at all unless you really need to. Yes remove dead or damaged wood and clean up broken branches, but keep it to minimum. This includes varieties such as Magnolia stellata,
When and how to prune
If you must prune to reduce size, start by selecting some of the taller or wider spreading branches and cut these back close to a union. Try to keep the natural look of the tree rather than pruning it to a ball, magnolias tend to look a little silly when pruned to tight shapes.
You may actually find that by pruning to hard a deciduous magnolia will actually respond by pushing out new growth that tends to go in the 'wrong direction', straight up.
Try not to prune magnolias at all when they are in active growth as they tend to weep or 'bleed'. Prune in autumn if you must. When you are pruning larger magnolia branches look the ridges near the joins in the branches and cut back to these, this helps prevent die back.