Sep 21, Prune up to 1/3 of a magnolia bush each season all the way back to the ground to encourage new growth from the base of the plant. Prune a second time in mid-summer to cut back on the current season's stumpclearing.buzzg: Springfield VA. G&V. G&V provides the best tree trimming service in Springfield, Virginia and the surrounding areas. Brandon Ave SuiteSpringfield, VA - Phone:Estimated Reading Time: 3 mins. When to Prune a Magnolia Tree.
For magnolias that bloom in early spring, the best time for pruning is soon after the tree has finished blooming. This can be late spring or early summer, depending on the climatic zone. Pruning too late in the season will result in fewer blossoms the following stumpclearing.buzzg: Springfield VA.