When to Prune the Top Types of Magnolias
Among the most ancient flowering species, magnolias were keeping company with the dinosaurs. They’ve had a lot of time to evolve, so there’s quite a bit of variety in the family. Some magnolias have multiple stems or trunks, and others, like the Southern magnolia, have just one trunk. Some are deciduous, meaning they drop their leaves for the winter, and some are evergreen. Although there are thousands of different magnolias, you’re probably growing one of the four that do best in home gardens. These pruning rules are based on when each of these magnolias flowers. Hardy in USDA Zones 6–10, Southern magnolia (Magnolia grandiflora) does everything in a big way. It can reach 60 to 80 feet tall and it has enormous white flowers that can reach a foot in diameter. It grows symmetrically, so little pruning is needed. In fact, it’s best to leave the lower branches in place, so they touch the ground and cover the dead leaves the tree sheds naturally almost every day. If you do need to trim this evergreen, wait until it finishes blooming in summer. Saucer magnolia or pink tulip tree (Magnolia x soulangeana) has multiple stems and gets about 25 feet tall and wide in Zones 4–9. It’s best to decide how many trunks you want to keep while this tree is young, and shape it so the trunks and branches don’t cross each other. Its pretty flowers appear in spring, so time any pruning for after the blooms have faded. Once this deciduous tree has matured—at about 20 years old—prune as little as possible, because it heals slowly. Star magnolia (Magnolia stellata) will grow to 15 to 20 feet tall with multiple stems in Zones 4–8. It loses its leaves in the fall, and in spring the star-shaped blooms appear on bare branches (plant it in front of evergreens or a dark-colored wall so the flowers stand out). Prune your star magnolia after it blooms to shape it within the first five years after you’ve planted it. Sweetbay magnolia (Magnolia virginiana) doesn’t bloom until the summer. Another multi-stemmed magnolia that will need pruning when it’s young, it’s the exception to the usual pruning time. You need to catch this one at the end of the winter, before its growth spurt. Once it starts growing in the spring, you run the risk of pruning off that summer’s flowers. Sweetbay magnolia will grow in Zones 5–10, and it can be a small, 15-foot, deciduous tree in New York or it can shoot up to 60 feet in the deep South, where it tends to be evergreen.
Pruning Tools and Tips for Magnolias
Your magnolia probably won’t ever need major surgery, unless a storm hits it hard or it got off on the wrong foot in its youth. With young magnolias, make cuts with pruning shears. If a small branch doesn’t fit easily inside your open pruners, you should use loppers, but use a pruning saw for branches over one inch in diameter.
