Magnolia grandiflora

Updated: Aug 19


If you are unfamiliar with Southern magnolias, then you are unaware of its deep ties to the American South. The genus, Magnolia, honors 17th and 18th century French botanist Pierre Magnol, perhaps at the time when France played a significant role in the South. Discussing its history would indeed be a lengthy narrative, so let's look at a couple brief examples from the Arbor Day Foundation:

The Jones Magnolia, planted in 1839 in Arkansas’ Washington State Park and still thriving today, stands near the inn where Sam Houston and others gathered to plan the independence of Texas. The blacksmith shop where James Black and Jim Bowie made the first Bowie Knife also stood near this location.

We have the much anticipated Magnolia Network, an emerging media empire, once a regional influence with its sphere limited to Waco, Texas is now blossoming across the country. Steel Magnolias (yes, I'm dating myself), is a movie about the strength of small-town Louisiana women and their challenges. These references to the Magnolia appear to be testaments to enduring qualities by a uniquely Southern plant species with heady fragrance and lasting evergreen boughs.


Planting M. grandiflora in the West has its challenges, which has been made more apparent during our long droughts. Look around and you might find lush, healthy examples in equally lush landscapes, such as the trees located in the front lawn at the Campbell Community Center (photographed below). However, more readily found are Southern magnolias in drought stressed conditions (also shown below). For example, as street trees along Palo Alto's University Avenue, their health appears to be directly determined by how much water they are receiving along the avenue. While some trees are undoubtedly receiving supplemental irrigation, others appear stressed and in dry conditions, receiving little to no water. For landscape designers, placing M. grandifloras means understanding site conditions for long-term survival. California is not the humid, swampy parts of the South, and we should design accordingly.


facts

Botanical Name: Magnolia grandiflora

Magnolia: Honoree, botanist Pierre Magnol

Grandiflora: Having large flowers

Common Name: Southern magnolia; Bull Bay magnolia

Family Name: Magnoliaceae


Origin: Southeastern United States


design considerations


Positioning: Background, statement tree, park

Garden Themes: Sub-tropical/tropical, formal, sensory, pollinator

Uses: Cut flower and foliage, shade tree, specimen, accent, large hedge or screen


identifying characteristics


Type: Evergreen tree

Form: Pyramidal, round (dense when well hydrated)

Texture: Coarse

Size: 80' tall by 50' wide


Outstanding Feature(s): Flower, fragrance, foliage


Bark: Dark warm gray, smooth when young becoming patchy with age

Leaf:

  • Type: Simple

  • Arrangement: Alternate

  • Shape: Elliptical

  • Margin: Entire

  • Color: Dark green above, copper/russet underneath

  • Surface: Stiff, smooth and glossy above, tomentose underneath

Flower: Spring to summer. Large, solitary, saucer form, white to cream as they age. Highly fragrant.

Fruit: Autumn. Aggregate follicle. Brown with fleshy red seeds.


cultural requirements, tolerances & problems


Sunset Zones: 4-12, 14-24; H1, H2

USDA Zones: 6-10


Light: Full sun to partial shade

WUCOLS SF Bay Area Hydro Zone: Moderate

Soil:

  • Texture: Clay, loam, well-composted

  • Moisture Retention: Well-drained

  • pH: Very acidic to slightly alkaline

Tolerances: Salt, wet conditions, urban conditions (with supplemental moisture)

Problems:

  • Branch Strength: Medium

  • Insects: Invasive shot hole borer, aphids, scale, spider mites

  • Disease: Armillaria, root rot, verticillium


citations & attributions


Extension Gardener Plant Toolbox. "Magnolia grandiflora." North Carolina State University, Raleigh. Accessed on July 31, 2021, from https://plants.ces.ncsu.edu/plants/magnolia-grandiflora/.


Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.


SelecTree. UFEI. "Magnolia grandiflora Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on Aug 1, 2021, from https://selectree.calpoly.edu/tree-detail/845.


Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on August 1, 2021.

https://ucanr.edu/sites/WUCOLS/Download_WUCOLS_IV_List/.


Photos:

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