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Magnolia Trees: Planting, Growing, and Pruning Magnolias

How to Grow a Magnolia Tree

Magnolia Tree Blossom
Photo Credit
W. Nieuman
Botanical Name
Magnolia spp.
Plant Type
Sun Exposure
Bloom Time
Flower Color
Hardiness Zone

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Planting, Growing, and Pruning Magnolias

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With large, fragrant flowers and magnificent branch structures, magnolia trees are one of the oldest flower plants on Earth. Large or small, evergreen or deciduous, there’s a magnolia just right for your space. Learn how to plant, grow, and care for magnolias.

About Magnolias

Magnolias aren’t just for southern gardeners. The genus Magnolia is varied and encompasses hundreds of plant species, with many more cultivars developed. Today, magnolias are available in all sizes, from small shrubbery to large shade trees, deciduous or evergreen. Some are cold, hardy, and frigid, as in zone 4.

Magnolias are believed to be among the oldest flowering plants, at about 100 million years old. They have been blooming in spring and summer since dinosaurs roamed the earth. Is the magnolia in your yard a direct descendant of one whose leaves were munched by a Hadrosaurus? 

The giant of the family, southern magnolias (M. grandiflora), are evergreen trees with large, leathery leaves found throughout the American South and grow to gigantic proportions, often reaching 60 to 80 feet tall. Leaves can be epically sized as well, and on larger trees, can be a foot long. The blooms are dinner-plate-sized, and the fragrance is fantastic.

Magnolias come in so many sizes that they can be used for every landscape situation, from huge shade trees to flowering specimens, privacy hedges and borders, screening plantings, and even in beds and containers. When shopping, choose magnolias based on flowering time, hardiness zone, color, and mature size.

Planting

When to Plant Magnolias

Magnolias can be planted in spring or fall. If planting in autumn, get the tree in the ground 4-6 weeks before the first frost to allow time to grow new roots. Bare root stock received in spring should be planted as soon as received.

Where to Plant Magnolias

While specific cultivar needs may vary, most members of the Magnolia genus prefer full sun to light shade and, in hotter climates, need protection from the intense afternoon sun. Their branches can be brittle, so pick a site protected from the wind. 

Magnolias grow large, thick, shallow root systems and should be kept away from building foundations or sidewalks. Check the tag and visualize the mature size of the tree or shrub. Some magnolias are enormous, while others are small enough to grow in containers. 

When planting, select a site with the following:

  • Full to partial sun. Choose a site with morning and midday sun but afternoon shade in hotter climates. 
     
  • Moist but well-drained sites are best. Very dry or wet sites are not suitable. 
     
  • Acidic soil, pH 5.5-6.5, is best. 

How to Plant Magnolias

Planting magnolias is easy, and the same methods are used for planting other nursery stock. 

  1. Remove all sod from an area twice as large as the hole you will dig. 
     
  2. Dig a hole the same depth as the root ball and at least twice as wide. The hole should look like a shallow bowl, not a coffee can.
     
  3. Loosen the soil on the sides and bottom of the hole. A hard, compact edge or bottom is difficult for roots to penetrate (and for water to drain).
     
  4. Remove the magnolia from its container and prune any circling or girdling roots. Rootbound plants will benefit from scoring of the root ball to stimulate new growth in outward directions. Remember to remove the wire basket if your tree was balled and burlapped.
     
  5. Place and test fit the magnolia in the hole. Check for depth and ensure no roots are bent over or circling the hole. The top of the rootball should be level with the soil surface. Enlarge the hole if necessary. For grafted magnolias, ensure the graft union is above the soil level after planting.
     
  6. Backfill the hole with the soil you removed, ensuring the tree is kept vertical while filling. Stop when the hole is about halfway refilled and tamp the soil firmly around the roots to remove air pockets, then give it a good drink of water (but don’t flood the hole). Continue filling the soil around the roots and firming it with your hands. Water again when complete.
     
  7. Spread mulch around the tree, about 3 to 4 inches thick. Spread the mulch evenly in a circle extending 2-3 feet from the trunk. Don’t let the mulch touch the trunk–keep a few inches of separation. The final mulch job should look like a flattened donut, not a volcano.
Magnolia tree blossoms. Credit: Mike Pellinni
Growing

How to Grow Magnolias

Newly planted magnolias will need watering several times per week, depending on the weather, and weekly after the first month or two. Magnolias don’t need to be fertilized. However, during the first 2 t0 3 years, growth can be encouraged by applying a balanced (10-10-10) fertilizer product in spring. 
 

How to Prune Magnolias

When young, magnolias may be pruned for shaping. Large cuts on older trees should be avoided, as pruning wounds often heal slowly. Prune after flowering is complete for the year. Damaged branches may be removed as soon as noticed.

How to Propagate Magnolias

Magnolias can be grown from seed or by cuttings, but while more difficult, cuttings are preferred. New magnolias grown from cuttings will likely bloom in a few years, while seed-grown plants may take over a decade to blossom. Rooting is slow and takes 5 to 10 weeks. 

Generally, the larger a cultivar or species of magnolia when mature, the more difficult they are to root. Bottom heat and higher concentrations of rooting compound are used to increase success. Big box stores often only carry the general-purpose, weaker rooting solutions, so you may have to order online.

  • Prepare your container(s). A mix of coir and perlite or pure perlite works. It should be damp. Fill the container at least four inches deep. Drainage holes are a must. 
     
  • Take terminal cuttings in mid to late summer (July and August). Cutting wood should be firm but not yet hard and about 6 to 8 inches long. Immediately place the cuttings in a jar of water to prevent them from drying out. Don’t wait until you get back to the house. 
     
  • Remove all but the last pair of leaves on the cutting. If those two leaves are large, cut them in half.
     
  • Using a knife or your pruning shears blade, lightly scratch up the base of the twig, wounding the thin bark.
     
  • Don’t skip this step. Dip the cutting in a rooting hormone solution. You’ll want a strong one here, 8-10,000 ppm or 0.8-1.0% IBA. NAA (Naphthalene Acetic Acid) is often more effective for magnolias but is not as commonly available. Untreated magnolia cuttings root poorly, if at all. 
     
  • Use a pencil to make a hole, and stick the cuttings in moist media. Gently firm the material around the cuttings.
     
  • Once stuck, cover cuttings with a plastic humidity dome or a clear plastic bag tied around the pot to keep it moist. Misting will keep humidity high until cuttings are rooted. Place the containers on a heat mat set at 75-8℉ until rooting has occurred.
     
  • Place stuck and covered cuttings under supplemental lighting for faster root development. 12 hours per day of light works well.
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Wit and Wisdom
  • Magnolias were around before bees evolved and were pollinated by beetles. 
     
  • Magnolia roots may extend up to three times as far from the tree as the branches. Take care when applying pesticides to lawns or weed killers nearby.
     
  • Many magnolias dump their huge leaves in spring, and the fruits can also make quite a bit of litter. Grass often struggles under magnolias, so consider planting in a spot where their litter won’t make a problem.

Southern magnolia (Magnolia grandiflora) fruits. Credit: Tamu1500


 

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About The Author

Andy Wilcox

Andy Wilcox is a flower farmer and master gardener with a passion for soil health, small producers, forestry, and horticulture. Read More from Andy Wilcox

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