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Publication #FPS-360

Magnolia kobus var stellata 'Green Star' 'Green Star' Star Magnolia1

Edward F. Gilman2

Introduction

Star magnolia is one of the hardiest of the magnolias (Fig. 1). It is a small tree or large shrub, 15 feet tall with a 10- to 15-foot spread. Typically branching close to the ground, the multi-stemmed form develops with a dense head of foliage. Star magnolia makes a wonderful patio, lawn specimen, or accent tree. Lower foliage can be removed to show off the trunk and to create more of a tree form. Otherwise, the persistent lower branches and oval to round form lend a “large bush” look to the plant. When planted against a dark background, the branching pattern and light gray trunk will show off nicely, particularly when lit up at night. The leafless winter silhouette looks great shadowed on a wall by a spotlight at night. The white flowers have a slight touch of pink coloration, and are produced in spring before the leaves appear, even on young plants. Flowers are usually not as sensitive to cold as saucer magnolia, but they can still be injured if cold weather arrives during flowering.

Figure 1. 

'Green Star' star magnolia


[Click thumbnail to enlarge.]

General Information

Scientific name: Magnolia kobus var. stellata 'Green Star'
Pronunciation: mag-NO-lee-uh KOE-bus variety stell-AY-tuh
Common name(s): 'Green Star' star magnolia
Family: Magnoliaceae
Plant type: shrub
USDA hardiness zones: 5 through 8 (Fig. 2)
Planting month for zone 8: year round
Origin: not native to North America
Uses: near a deck or patio
Availability: somewhat available, may have to go out of the region to find the plant

Figure 2. 

Shaded area represents potential planting range.


[Click thumbnail to enlarge.]

Description

Height: 12 to 20 feet
Spread: 12 to 18 feet
Plant habit: round
Plant density: moderate
Growth rate: slow
Texture: medium

Foliage

Leaf arrangement: alternate
Leaf type: simple
Leaf margin: entire
Leaf shape: obovate
Leaf venation: pinnate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches
Leaf color: green
Fall color: yellow
Fall characteristic: not showy

Flower

Flower color: white; pink
Flower characteristic: spring flowering

Figure 3. 

Flower of 'Green Star' star magnolia


[Click thumbnail to enlarge.]

Fruit

Fruit shape: irregular
Fruit length: 1 to 3 inches
Fruit cover: dry or hard
Fruit color: brown
Fruit characteristic: inconspicuous and not showy

Trunk and Branches

Trunk/bark/branches: not particularly showy; typically multi-trunked or clumping stems
Current year stem/twig color: brown
Current year stem/twig thickness: medium

Culture

Light requirement: plant grows in part shade/part sun
Soil tolerances: clay; sand; loam; acidic; slightly alkaline;
Drought tolerance: moderate
Soil salt tolerances: poor
Plant spacing: 36 to 60 inches

Other

Roots: usually not a problem
Winter interest: plant has winter interest due to unusual form, nice persistent fruits, showy winter trunk, or winter flowers
Outstanding plant: not particularly outstanding
Invasive potential: not known to be invasive
Pest resistance: long-term health usually not affected by pests

Use and Management

Star magnolia is intolerant of root competition or dryness, and plants grow slowly, perhaps one foot per year. Plant in the full sun in a rich, porous, and slightly acid soil. It is hard to transplant successfully and in the north should be moved balled and burlapped when actively growing. In USDA hardiness zones 7 and 8, transplant in late winter while the plants are still dormant, or after the growth flush in the spring or plant from containers at any time.

There are a few other cultivars: 'Jane Platt' — new, superior type with many pink petals when opening; 'Keiskei' — flowers purplish on the outside; 'Rosea' (pink star magnolia) — pale pink flowers; 'Rubra' (red star magnolia) — purplish flowers, darker than 'Rosea'; and 'Waterlily' — pink flower buds, white flowers, flowers larger with narrower petals. The “Little Girl" hybrids have an upright habit and flower later than the species, thus avoiding frost injury in most years. They include 'Ann', `Betty', 'Jane', 'Judy' `Randy', 'Ricki,' and 'Susan'.

Pests and Diseases

Basically trouble free although scales of various types may infest twigs and leaves. Magnolia scale is the most common scale and can be one half inch across. Overwintering scales can usually be controlled with horticultural oil.

Tulip poplar weevil (sassafras weevil) feeds as a leaf miner when young and chews holes in the leaves as an adult.

None particularly troublesome. Magnolia may be subject to leaf spots, blights, scabs, and black mildews caused by a large number of fungi or bacteria. Leaf spots rarely require chemical controls. Rake up and dispose of infected leaves.

Canker diseases will kill branches. Cankers on branches can be pruned out. Keep trees healthy with regular fertilization and by watering in dry weather.

Verticillium wilt may cause death of a few branches or may kill the tree. Prune out dead branches and fertilize regularly.

Footnotes

1.

This document is FPS-360, one of a series of the Environmental Horticulture Department, UF/IFAS Extension. Original publication date October 1999. Reviewed February 2014. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Edward F. Gilman, professor, Environmental Horticulture 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.