Things You'll Need
A plant's hardiness is the measure of how well it tolerates cold temperatures, frost and ice. A magnolia tree's hardiness depends upon the cultivar, as some are more able to tolerate the cold than others. No matter which type of magnolia you are growing, the first three years of the tree's life are the most critical to its later success. In maturity, the tree can handle the ravages of winter. The immature tree, however, requires protection.
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Construct a windbreak around the immature magnolia tree. Pound four stakes into the ground, equally spaced, around the magnolia tree. Stretch burlap around the frame and staple or wire it to the stakes. This should protect the young tree during particularly windy weather and from salt spray.
Prune the evergreen magnolia in the winter. Remove any dead or dying twigs or branches by cutting them off at their base. Deciduous magnolias heal slowly after pruning, so hold off on pruning until the weather is warmer.
Top-dress the soil at the base of the magnolia tree with a 5-inch layer of mulch. This will help protect the roots from the cold. Keep the mulch at least 6 inches from the base of the tree and spread it out to the drip-line, completely encircling the tree.
Water the magnolia tree during the warmer, drier days of winter, when the soil is likely to thaw a bit and then refreeze. Provide it with half the amount of water you do during the growing season.