Magnolia trees can be evergreens, semi-evergreens or deciduous trees, depending on where you live and what species you have. As with any trees, magnolias are best pruned during their dormant season. However, you should trim off dead branches--and also diseased and broken branches--as soon as possible to prevent insect and disease problems. As with any pruning job, use clean, sharp pruning tools. Wipe down the blades with rubbing alcohol after pruning diseased plants.
Search for the parent branch from where the dead branch is growing. If that branch is weak or is also dying, trace that branch to its parent branch and prune there instead, using the pruning shears or saw.
Analyze the thickness of the branch you'll cut. f it is more than 1½ inch in diameter, make three cuts to successfully remove the branch without ripping. If it’s smaller than that, proceed to Step 4.
Saw from the bottom to top of the branch about 6 to 12 inches from the parent branch, only about 1/3 of the way. You don’t need to complete this cut. Make another cut 3 inches closer to the parent branch, but from the top. Keep going until the branch falls off.
Prune ½ inch above the parent branch. Use one hand to hold the branch and the other to make the cut. Cut at an angle that will allow rainwater to drip to the ground. Make a smooth cut. It should not be jagged. Do not tear or pull at the branch. Cut from start to finish. Use pruning shears, such as loppers, or a saw for thicker branches.