Perfect for small gardens, the gray-barked branches of the Oyama magnolia (Magnolia sieboldii) bear green leaves with downy undersides. The highlight of the growing season is the production of downward-facing white flowers that are fragrant in late spring and early summer. Additional seasonal interest follows in autumn, with the display of pink seedpods and golden yellow foliage.
The Magnolia sieboldii is native to eastern Asia, primarily to Japan, Korea and eastern China. A subspecies, sinensis, is native to western China's forests. "Oyama" refers to an area on the southern Japanese island of Okinawa.
Growing to a mature height of 25 feet and spreading to 40 feet in its native range, Oyama magnolia is a spreading, deciduous large shrub or small tree. Its bark is smooth and light gray. In garden cultivation this plant doesn't grow as large, only reaching a typical height of 12 to 15 feet and a spread of 8 to 10 feet.
Its dark green leaves are 6-inch-long ovals with a gray-green underside. The leaves are simple, meaning each leaf is complete, without any lobes. In autumn they turn golden yellow before dropping. Leaves are arranged in an alternating pattern along the length of the branches.
In late spring to early summer, branch tips bear a deliciously fragrant cup-shaped white flower, about 4 inches in diameter. The flower buds are white and look like small lanterns. Normally the flower droops, or faces horizontally or downward rather than being held conspicuously upright. The blossom has 12 petals that surround a cluster of crimson stamens. After blooming, the flower ripens to a bright pink seedpod.
Grow Oyama magnolia in USDA Hardiness Zones 6 through 9. Alternatively, gardeners in western North America will be more familiar with growing it in Sunset Climate Zones 4 through 9 and 14 through 17. This species is more tolerant of wind than many other magnolias.
Plant Magnolia sieboldii in a moist, well-draining soil that is rich in organic matter and has an acidic pH (6.5 and lower). It does best in a partial shade, receiving 2 to 4 hours of direct sunlight daily. Mimic the dappled, changing light patterns of a forest setting to encourage best growth and flowering on this magnolia.