Magnolia sieboldii is a large deciduous shrub or small tree 5–10 m (16–33 ft) tall.

They are pendulous, cup-shaped, 7–10 cm diameter, and have 6-12 tepals, the outer three smaller, the rest larger, and pure white; the carpels are greenish and the stamens reddish-purple or greenish-white.

It is one of the hardiest magnolias, successful in cultivation as far north as Arboretum Mustila in Finland.

The cultivar 'Colossus' has gained the Royal Horticultural Society's Award of Garden Merit.

[4] Called mongnan or mokran (목란/木蘭), Siebold's magnolia is the national flower of North Korea.