Introduction
A striking tree in summer or winter. Dropping its large, six-inch leaves in fall without any spectacular display of color, Kobus Magnolia forms an attractive winter specimen with its rounded silhouette and multiple trunks originating close to the ground. Supposedly grows 30 to 40 feet tall but is most often 25 feet or less in an open, sunny landscape site and is capable of reaching 75 feet in height in its native forest habitat. In an open site, spread is often greater than height with 25-foot-tall trees 35 feet wide if given the room to grow unobstructed. Branches gracefully touch the ground on older specimens as the tree spreads, in a manner not unlike open-grown Live Oaks. Allow plenty of room for proper development.
Credit: Ed Gilman
General Information
Scientific name: Magnolia kobus
Pronunciation: mag-NO-lee-uh KOE-bus
Common name(s): Kobus Magnolia, Northern Japanese Magnolia
Family: Magnoliaceae
USDA hardiness zones: 5A through 8A (Fig. 2)
Origin: not native to North America
Uses: specimen; container or planter
Availability: somewhat available, may have to go out of the region to find the tree
Description
Height: 25 to 30 feet
Spread: 25 to 35 feet
Crown uniformity: symmetrical
Crown shape: round, spreading
Crown density: dense
Growth rate: slow
Texture: coarse
Foliage
Leaf arrangement: alternate (Fig. 3)
Leaf type: simple
Leaf margin: entire, undulate
Leaf shape: obovate, elliptic (oval)
Leaf venation: brachidodrome, pinnate
Leaf type and persistence: deciduous
Leaf blade length: 4 to 8 inches
Leaf color: green
Fall color: yellow
Fall characteristic: showy
Flower
Flower color: white/cream/gray, pink
Flower characteristics: very showy
Fruit
Fruit shape: irregular, elongated
Fruit length: 1 to 3 inches
Fruit covering: dry or hard
Fruit color: pink, red
Fruit characteristics: attracts birds; showy; fruit/leaves not a litter problem
Trunk and Branches
Trunk/bark/branches: branches droop; not showy; typically multi-trunked; thorns
Pruning requirement: little required
Breakage: resistant
Current year twig color: green, brown
Current year twig thickness: medium, thick
Wood specific gravity: unknown
Culture
Light requirement: full sun, partial sun or partial shade
Soil tolerances: sand; loam; clay; slightly alkaline; acidic; well-drained
Drought tolerance: moderate
Aerosol salt tolerance: low
Other
Roots: not a problem
Winter interest: yes
Outstanding tree: yes
Invasive potential: little invasive potential
Ozone sensitivity: tolerant
Verticillium wilt susceptibility: susceptible
Pest resistance: free of serious pests and diseases
Use and Management
The lightly-fragrant blooms which appear in spring before the new leaves unfold are ivory-colored to pale pink and four inches in diameter. Young trees flower poorly. The pink fruits which develop split open to reveal bright red seeds, which sway from slender threads before dropping to the ground.
Kobus Magnolia should be grown in full sun or partial shade on any well-drained soil. Probably not for poorly-drained areas but supposedly tolerant of soil with an alkaline pH.
The cultivar `Wada's Memory' has black-green leaves, large, six-inch blooms and an upright or columnar growth habit (at least in youth). It will be available at selected nurseries.
Propagation is easily done by cuttings.
Pests and Diseases
No pests or diseases are of major concern but occasionally bothered by scale as are other Magnolias.
