Answer: I believe I answered your first magnolia question yesterday. I've taken the following information directly from the article (March/April 1998, by Eliot Tozer) I mentioned in my previous response:
What to Buy and How to Plant
When you shop for a magnolia, look for large, vibrant leaves and vigorous growth on the ends of twigs. A good time to shop is in the spring when you may see blossoms. It's fine to buy plants that are already in bloom. Because magnolias have soft, fleshy roots that damage easily, they're difficult to plant compared to many other trees. (Once established, however, magnolias forgive occasional neglect.) If possible, buy plants in containers.
When selecting a site, keep in mind the ultimate size of the plant. Magnolias don't like to be transplanted. Space trees about 25 feet apart. Because blossoms and leaves are susceptible to wind damage, try to choose a protected site. A north-facing location might delay bloom until after the last frost, saving the blossoms. Like many plants, magnolias prefer well-drained soil that's rich in organic matter and has a pH of 5.5 to 6.5.
Plant balled-and-burlapped magnolias when they're dormant, or in late spring after growth has started. Trees grown in
containers, however, can be planted whenever the soil is moist. As for the planting hole, the old rule applies: a $10 hole for a $5 plant. Make the planting hole twice as wide as the rootball. Pruning roots at planting time stimulates faster growth early on, but the gain is lost after a year or so.
Because magnolias are surface feeders, plant them no more than an inch deeper than they were planted at the nursery. Fertilize lightly with a 5-10-5 formula, and mulch to retain soil moisture and to discourage weeds. Anchor the tree until it becomes established.
Pruning and Mulching
It isn't necessary to prune branches to encourage growth after transplanting, although you can prune an ungainly plant to improve its appearance. In cold-winter climates, prune precocious magnolias in summer after they've bloomed. Prune all others when they're dormant. Keep a circle of mulch around the tree, and continue fertilizing as needed. However, so the plant will stop producing new growth and will harden off, don't fertilize it after midsummer.
Magnolias can take an irritatingly long time to bloom, anywhere from 2 or 3 years to 12 to 15 years (M. campbellii can take 20).
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