Magnolia sieboldii, Oyama magnolia
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Broadleaf Deciduous Trees

Magnolia sieboldii

Oyama magnolia

MagnoliaceaeJapan, Korea, Manchuria, China

At a Glance

TypeTree
HabitSpreading
FoliageDeciduous
Height10-20 feet (3-6 m)
Width10-15 feet (3-4.6 m)
Maturity15 years

Growing Zones

USDA Hardiness Zones

5 - 8
Zone 5
Zone 6
Zone 7
Zone 8
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Attracts Pollinators
Fragrant (moderate)
Maintenancelow

Overview

Magnolia sieboldii is a deciduous large shrub or small tree reaching 10-20 feet (3-6 m) tall with a spread of 10-15 feet (3-4.6 m), developing a rounded, spreading to somewhat open crown. Leaves are alternate, simple, obovate to elliptic, 3-6 inches (8-15 cm) long, medium to dark green above with a pale, slightly pubescent underside. Foliage emerges after flowering begins and turns yellow to bronze in fall, though color is variable and often brief. Flowers are nodding to pendulous, cup-shaped, 3-4 inches (8-10 cm) across, with 6-9 white tepals surrounding a prominent central boss of crimson to maroon stamens. Bloom occurs on current season's leafy shoots from late May through July, with sporadic flowers continuing into August. Flowers are fragrant, with a citrus-like scent. Unlike spring-blooming magnolias, the flowers appear after leaves have developed, and the nodding habit means flowers are best viewed from below. Aggregate fruit, 1-2 inches (2.5-5 cm) long, ripens in September to October, splitting to reveal red-orange seeds suspended on thin threads. Growth rate is slow to moderate at 6-12 inches (15-30 cm) per year. Trees are generally long-lived and free of serious pest or disease problems. Shallow, fleshy root system is sensitive to soil disturbance and compaction.

Native Range

Native to Japan, Korea, Manchuria, and adjacent parts of China. Occurs in mountain woodlands and forest margins at elevations of 1,500-5,000 feet (450-1,500 m), typically in moist, acidic soils with cool root zones under partial canopy cover.

Suggested Uses

Commonly planted as a specimen tree in woodland gardens and partially shaded borders where the nodding flowers can be viewed from below. Effective planted on slopes or elevated positions above paths and seating areas. Spacing of 10-15 feet (3-4.6 m) from other trees. Shallow root system and sensitivity to soil disturbance make it unsuitable for areas with heavy foot traffic or frequent cultivation.

How to Identify

Distinguished by nodding, cup-shaped white flowers 3-4 inches (8-10 cm) across with a prominent central boss of crimson stamens, appearing after leaves have developed in late spring through summer. Leaves are obovate, 3-6 inches (8-15 cm) long, paler and slightly pubescent beneath. Distinguished from Magnolia wilsonii by broader leaves, fewer tepals (6-9 vs. 9-12), and a more compact growth habit.

Appearance

Size & Dimensions

Height10' - 20'
Width/Spread10' - 15'

Reaches mature size in approximately 15 years

Colors

Flower Colors

white
red

Foliage Colors

green

Fall Foliage Colors

yellow
bronze

Bloom Information

Bloom Period

~5 weeks
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SpringSummer
Flowers appear from late May through July, with sporadic blooms continuing into August. Bloom period extends 4-6 weeks total. Unlike most magnolias, flowers open after leaves have developed. Individual flowers last 5-7 days. The nodding flower orientation means the crimson stamens are most visible from below or at eye level on smaller specimens.

Detailed Descriptions

Flower Description

White with crimson stamens

Foliage Description

Medium to dark green above, pale beneath

Growing Conditions

Sun Requirements

Partial Shade
Requires 3-6 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.0 - 6.5(Acidic)
357912
Soil Types
loampeatsand
Drainage
well drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

8-12 years

Care & Maintenance

Care Guide

Water regularly during the first two growing seasons to establish the fleshy root system. Established trees require supplemental water during dry periods exceeding 2 weeks, as drought stress causes premature leaf drop and reduced flowering the following season. Plant in part shade with 3-6 hours of direct light; morning sun with afternoon shade is preferred, particularly in warmer zones. Protect from hot, drying winds. Mulch the root zone with 3-4 inches (8-10 cm) of organic material, keeping mulch 6 inches (15 cm) from the trunk, to maintain cool, moist soil conditions. Avoid soil disturbance around the shallow root system; do not cultivate or dig within the dripline. No serious pest or disease problems. Scale insects may occur occasionally.

Pruning

Prune in late spring to early summer (May through June) after the primary flowering flush, if needed. Magnolias generally require minimal pruning; remove dead, damaged, or crossing branches. Avoid heavy pruning, as the slow growth rate means recovery takes several years. Do not prune in fall or winter, as wounds heal slowly and may invite disease entry during the dormant season.

Pruning Schedule

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late spring

Maintenance Level

low

⚠️ Toxicity Warning

Non-toxic