Caring For Southern Magnolia: An Expert Answers Common Questions

When my Southern magnolia tree (Magnolia grandiflora) is blooming, I don't have to see it to know. I can smell it from 20 feet away. Waxy, white blossoms up to 10 inches across crown its glossy, evergreen leaves. Some flowers may smell as good, but none smell better. With magnolias in bloom or nearing bloom, I have been getting a lot of questions about this native stalwart—and I have finally answered them. Read below for all your questions answered about this staple Southern tree.

How Big Does The Southern Magnolia Tree Grow?

That depends on where it's growing, but the average tree matures anywhere from 60-80 feet tall and 40-feet wide after many years. That's BIG. Fortunately, home gardeners can plant more compact selections that won't swallow an entire yard. They include 'Teddy Bear' (16- to 20-feet tall, 10- to 12-feet wide), 'Brackens Brown Beauty' (35 feet tall, 15 feet wide), 'Little Gem' (20- to 25-feet tall, 10- to 15-feet wide), and 'Majestic Beauty' (35- to 50-feet tall, 20 feet wide).

Where Can You Grow The Southern Magnolia Tree?

Southern magnolia thrives in USDA Zones 6 to 10. It likes acidic to slightly alkaline, well-drained soil, and full to partial sun. It also tolerates salt spray, so it's a good candidate for beach gardens. On the downside, in central and western Texas and Oklahoma, it is generally too hot and dry for this tree and the soil pH is often too alkaline.

Is It OK To Prune Southern Magnolias? How And When?

Sure—where do you think all of those magnolia branches for holiday decorations come from? I use hand pruners to do the work, shortening branches to the point where they join with another branch, so I don't leave obvious holes in the canopy. You can prune in spring, summer, late fall, or winter. Keep in mind that if you completely remove the lowest branches of a big tree, they probably won't be replaced by new ones.

What Should I Fertilize With And When?

Here's some shocking news: Southern magnolia doesn't need any fertilizer, so don't waste your money. Just plant it in a hole that's three times wider than the root ball, but no deeper. Fill in with the same soil you just dug out.

My Southern Magnolia Tree Has Never Bloomed. What Am I Doing Wrong?

Probably nothing. Unnamed, generic trees (that just say "Southern magnolia" on the tag) can take a long time to start blooming, especially if they're small. Named selections such as 'Little Gem,' 'Teddy Bear,' and Bracken's Brown Beauty' start blooming much earlier. If you want an absolute guarantee, buy a tree that already has flowers or flower buds on it.

My Magnolia Has A Brown Coating On The Undersides Of The Leaves. Is This A Disease?

Nope—the brown stuff is made up of tiny hairs and is called "indumentum." Many gardeners, Grumpy included, find the rich, brown undersides combined with the deep-green topsides to be quite attractive.

Lots Of Smaller Branches On My Magnolia Have Brown Leaves On The Ends. Why?

This is damage caused by a small beetle called a black twig borer. The female beetle bores a tiny, round hole on the underside of a twig and lays eggs inside. The larvae hatch and feed inside, hollowing out the twig, which then dies. The dead twig ends don't threaten the life of the tree, but they sure do make it ugly. Solution? Pick up any dead twigs that fall and throw them out with the trash. Remove any you can reach that haven't fallen by cutting three inches up from the holes into live wood and throw them out too.

What Can Protect The Fruit On My Southern Magnolia From Getting Eaten?

The Southern magnolia tree's fruit attracts squirrels, rabbits, and various kinds of birds. To protect your tree and ward off the wildlife, try spraying the tree with a cayenne pepper and water mixture (16 parts water, one part cayenne pepper). This mixture can help with other plants you find the squirrels are loving too—just be wary of spraying plants that are lower to the ground if you have animals or small kids.

What Are The Most Common Mistakes People Make When Planting Magnolias?

Common mistakes include planting them too deeply and too close to the house. The top of the root ball should be even with the soil surface and the tree should be planted at least 20 feet from your home.