Winter Care for Magnolia Trees

There are approximately 125 magnolia species, ranging from tall shrubs to large trees. Magnolias may be deciduous, semi-evergreen or evergreen. Among the species planted in U.S. gardens are the star magnolia (​Magnolia stellata​, USDA zones 4-9), sweetbay magnolia (​Magnolia virginiana​, USDA zones 5-9), southern magnolia (​Magnolia grandiflora​, USDA zones 6-10) and their cultivars. The most cold-hardy magnolia is a North American native, the cucumber tree magnolia (​Magnolia acuminata​, USDA zones 3-8).

While magnolia trees are cold-tolerant, the leaves and flower buds need protection from freezing temperatures, especially late frosts when the early spring blossoms appear on the tree. The smaller species are easier to protect from harsh winter weather, but location is essential for larger trees to ensure their survival when winter storms arrive. Plant your magnolia tree in a wind-sheltered area, preferably near a sunny south-facing wall which provides a warmer microclimate.

In general, magnolias need a well-drained, acidic soil in full sun or part shade. Magnolias are not tolerant of urban pollution or salty soils; plant well away from streets and sidewalks where salt is used to deice the hardscape.

Magnolias have wide-spreading roots, often twice the length of the tree's height. Like most trees, avoid planting a lawn under the tree. Instead, mulch the soil out to the edge of the canopy, or drip line. Though some magnolias tolerate drought, the trees grow best when watered regularly through the hot dry summer.

Fertilize with a slow-release 10-10-10 fertilizer in early spring, or a 20-20-20 liquid fertilizer monthly from spring to midsummer. Spread the fertilizer from the drip line inward to approximately 1 foot from the trunk. Alternatively, apply compost and well-decomposed manure to provide organic nutrients to the soil.

Magnolia tree care includes pruning. Put on your gloves and safety goggles, then sterilize your cutting tools by dipping the blades in Lysol and allowing to air dry. Prune your magnolia as needed after it flowers in spring and/or summer; avoid pruning in late summer, fall and winter, as the flower buds form in summer and fall. Prune to a shrub or tree form while removing broken, crossing, dead twigs and branches as well as water sprouts.

Protect a young magnolia tree in winter from hungry rodents and rabbits by wrapping hardware cloth around the trunk, then pound several 4- to 5-foot-tall stakes into the ground, 18 inches from the tree's trunk and branches. The stakes should be taller than the tree. Wrap two layers of burlap around the stakes and tree, then fill with dried leaves or loose straw to completely cover the tree. Add a burlap cover to keep the insulating material around the tree.

Generally, deciduous magnolias like the star magnolia need less protection than an evergreen species like a southern magnolia because the trees are dormant in winter. However, even deciduous trees need more protection when temperatures drop toward or below zero. Around both young and mature trees, add a 6-to-12-inch layer of loose mulch over the soil to insulate the roots. When the forecast predicts a freeze or late frost, water the tree thoroughly to protect the roots and prevent leaf browning in evergreen trees.

Remove the protective wrappings before the magnolia tree buds out in spring. Leave the stakes in place until all chance of a late frost is past. If the forecast predicts freezing temperatures, you can throw a frost blanket over the stakes and tree to protect the emerging leaves and flower buds.