Siebold Magnolia Tree Seeds | Oyama Magnolia| | (Magnolia sieboldii)

The nodding white cups. The magnolia that blooms after the leaves.

Magnolia sieboldii, the Siebold Magnolia or Oyama Magnolia, is the most refined and understated of the deciduous magnolias, producing pendant, cup-shaped white flowers with striking crimson stamens that hang downward on long stalks so that the full beauty of the flower interior can only be appreciated by looking up into the bloom from below or from a path running beneath the canopy. It blooms in late spring after the leaves have fully emerged, extending the magnolia season into early summer, and then continues producing scattered flowers through much of summer, giving it the longest effective bloom season of any deciduous magnolia. Named for Philipp Franz von Siebold, the German physician and botanist who introduced dozens of Japanese plants to western horticulture in the 19th century, it is grown by magnolia collectors worldwide for its delicate beauty and multi-season bloom. If you are looking to buy Siebold Magnolia seeds or grow this refined Japanese magnolia from seed, this is the magnolia worth approaching closely and looking up into.

• Cup-shaped white flowers with crimson stamens hanging pendant on long stalks, designed to be seen from below
• Blooms after leaves emerge and continues producing scattered flowers through much of summer
• The longest effective bloom season of any deciduous magnolia, from late May through July
• Compact form suitable for smaller gardens and woodland settings where larger magnolias are impractical
• Red-pink fruit cones in fall containing brilliant red seeds, ornamentally attractive through autumn

Things you probably did not know about the Siebold Magnolia

The pendant flower orientation is an adaptation to attract specific beetles for pollination. Magnolia flowers evolved before bees became the dominant pollinators and are primarily pollinated by beetles. The downward-hanging orientation of Siebold Magnolia flowers directs beetles that enter the flower downward into the floral chamber where pollen is concentrated, and the slight nodding makes it easier for beetles to exit with pollen attached. The crimson stamens that are visible in the center of the white petals serve as a landing target and nectar guide visible from a considerable distance.

It was the most frost-sensitive of the magnolias Sir Joseph Banks introduced from Japan to Kew Gardens. When Philipp von Siebold brought Magnolia sieboldii to Europe in the 1830s and specimens eventually reached Kew Gardens, it was noted as requiring more protection from late spring frost than most Japanese magnolias because of its relatively late bloom timing. The flowers, appearing when spring frosts are generally past, are actually less frost-vulnerable than early-blooming species, but the new foliage that emerges simultaneously is susceptible to late cold snaps.

The species has subspecies with slightly different characteristics across its range from Japan to Korea and China. Magnolia sieboldii grows naturally in the mountain forests of Japan, Korea, and northeastern China, with populations in different regions showing subtle differences in flower size, petal count, and leaf shape. Seed-grown plants from different geographic sources may express these regional variations, adding to the interest of growing from seed rather than from clonally propagated nursery material.

The red seeds are specifically adapted for bird dispersal. The brilliant red seeds that hang on threads from the opened fruit cones of Siebold Magnolia, like those of most magnolias, are designed to attract birds visually and offer a fat-rich coating that provides nutrition for the birds that consume and disperse them. The contrast between the red seeds and the white or tan cone background maximizes visual attractiveness to birds in the late summer forest.

Growing Details

• Botanical Name: Magnolia sieboldii
• Stratification: Required, 90 to 120 days cold moist stratification
• USDA Zones: 6 to 9
• Soil: Well-drained, moist, slightly acidic, rich in organic matter
• Light: Partial shade to full sun, best in dappled woodland light
• Height: 10 to 20 feet
• Spread: 10 to 20 feet
• Growth Rate: Slow to moderate, 6 to 18 inches per year

Plant it along a path you walk regularly in June and July so you will naturally look up into the hanging flowers. The crimson and white combination seen from below on a calm summer day is the entire point of this tree.