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Publication #ENH-540

Magnolia macrophylla: Bigleaf Magnolia1

Edward F. Gilman and Dennis G. Watson2

Introduction

This North American native tree is deciduous in most areas but semi-evergreen in the Deep South. Bigleaf Magnolia grows slowly to 30 to 40 feet and spreads 20 to 25 feet forming a rounded, broad canopy. The leaves of Bigleaf Magnolia are truly large, 12 to 32 inches long and 7 to 12 inches wide, when found in the wild and somewhat smaller when grown in landscapes. These leaves are bright green above with a fuzzy, silver/grey underside, creating a beautiful, two-toned effect with each passing breeze. From May to July the showy, fragrant blossoms appear, each 8 to 12-inch-wide, ivory-colored bloom having a slight rose tint at its base. These blooms are followed by the production of 2.5 to 3-inch-long, hairy, red, egg-shaped fruits. Bigleaf Magnolia trees must be 12 to 15-years-of-age before they begin to bloom.

Figure 1. 

Young Magnolia macrophylla: Bigleaf Magnolia


Credit:

Ed Gilman


[Click thumbnail to enlarge.]

General Information

Scientific name: Magnolia macrophylla
Pronunciation: mag-NO-lee-uh mack-roe-FILL-uh
Common name(s): Bigleaf Magnolia
Family: Magnoliaceae
USDA hardiness zones: 5B through 8B (Fig. 2)
Origin: native to North America
Invasive potential: little invasive potential
Uses: specimen; shade
Availability: somewhat available, may have to go out of the region to find the tree

Figure 2. 

Range


[Click thumbnail to enlarge.]

Description

Height: 30 to 40 feet
Spread: 20 to 30 feet
Crown uniformity: irregular
Crown shape: oval
Crown density: moderate
Growth rate: moderate
Texture: coarse

Foliage

Leaf arrangement: alternate (Fig. 3)
Leaf type: simple
Leaf margin: entire
Leaf shape: oblong, obovate
Leaf venation: pinnate, brachidodrome
Leaf type and persistence: deciduous
Leaf blade length: 12 to 18 inches, 18 to 36 inches
Leaf color: green
Fall color: no color change
Fall characteristic: not showy

Figure 3. 

Foliage


[Click thumbnail to enlarge.]

Flower

Flower color: white/cream/gray
Flower characteristics: very showy

Fruit

Fruit shape: elongated
Fruit length: 1 to 3 inches
Fruit covering: dry or hard
Fruit color: red
Fruit characteristics: attracts birds; showy; fruit/leaves a litter problem

Trunk and Branches

Trunk/bark/branches: branches droop; not showy; typically one trunk; thorns
Pruning requirement: little required
Breakage: resistant
Current year twig color: brown, green
Current year twig thickness: thick
Wood specific gravity: unknown

Culture

Light requirement: full sun, partial sun or partial shade
Soil tolerances: clay; sand; loam; acidic; slightly alkaline; well-drained
Drought tolerance: moderate
Aerosol salt tolerance: unknown

Other

Roots: not a problem
Winter interest: no
Outstanding tree: no
Ozone sensitivity: tolerant
Verticillium wilt susceptibility: susceptible
Pest resistance: resistant to pests/diseases

Use and Management

The tree may be rather short lived in many landscape sites unless its cultural requirements are met fairly closely. Branches break easily in wind storms and ice-laden branches snap off. The large leaves decompose slowly after they fall and blow around on the ground creating litter which some people will find objectionable. It may be best to locate this tree in a ground cover bed where leaves can drop and filter down beneath the low growing plants unseen.

Bigleaf Magnolia should be grown in full sun or partial shade on well-drained soil, and does not tolerate wet soil or drought. It appears to be somewhat picky in its requirements. In its native habitat it is found on rich, moist soils.

Cultivars include `Palmberg', with very large flowers, and `Purple Spotted', flowers with purple markings in the center.

Propagation is by seed or softwood cuttings.

Pests and Diseases

No pests or diseases are of major concern.

Footnotes

1.

This document is ENH-540, one of a series of the Environmental Horticulture, UF/IFAS Extension. Original publication date November 1993. Revised December 2006. Reviewed February 2014. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Edward F. Gilman, professor, Environmental Horticulture Department; Dennis G. Watson, former associate professor, Agricultural Engineering Department, UF/IFAS Extension, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.