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© Marco Mussita, some rights reserved (CC-BY) · iNaturalist
Overview
Aesculus turbinata is a large, broadly columnar to rounded deciduous tree reaching 50–70 feet (15–21 m) tall and 35–50 feet (10.5–15 m) wide at maturity. Leaves are palmately compound with 5–7 leaflets, each 8–16 inches (20–40 cm) long — among the largest in the genus — coarse-textured, dark green, with finely serrated margins. Individual leaves can span 24 inches (60 cm) across. Foliage turns orange-brown in fall, typically in October in zones 6–7. Erect flower panicles 6–10 inches (15–25 cm) long appear in May–June, composed of creamy white flowers with red and yellow basal markings. Fruit capsules are top-shaped (turbinate), 2–3 inches (5–8 cm), with a warty surface, containing 1–2 large, glossy brown seeds up to 1.5 inches (4 cm) in diameter. Growth rate is moderate at 12–18 inches (30–45 cm) annually; trees reach 30 feet (9 m) in approximately 20 years. Bark is gray-brown, developing shallow fissures and scaly plates on older trunks. Terminal buds are large and resinous, 1–1.5 inches (2.5–4 cm) long. Leaf blotch (Guignardia aesculi) is less prevalent on this species than on A. hippocastanum. Leaf scorch develops during prolonged drought. All parts are toxic if ingested.
Native Range
Native to Japan, found on Honshu, Hokkaido, and Shikoku islands. Grows in moist, rich deciduous mountain forests at 1,000–5,000 feet (300–1,500 m) elevation, often along streams and in valley bottoms.Suggested Uses
Planted as a shade tree in parks, arboreta, and large residential properties at 35–45 foot (10.5–13.5 m) spacing. Large leaf size and coarse texture require open sites where leaf litter can be accommodated. Not suited to small gardens, narrow planting strips, or areas with restricted root space.How to Identify
Appearance
Size & Dimensions
Height50' - 70'
Width/Spread35' - 50'
Reaches mature size in approximately 25 years
Bloom Information
Flowers May through June in zones 5–8. Bloom timing is approximately 1–2 weeks later than A. hippocastanum in the same climate. Individual panicles last about 2 weeks. In zone 8, bloom may begin in late April.Detailed Descriptions
Flower Description
Creamy white with red and yellow basal markingsFoliage Description
Dark green palmately compound leaves with 5-7 large leaflets, turning orange-brown in fallGrowing Conditions
Sun Requirements
Requires 6-10 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
Care & Maintenance
Care Guide
Water deeply every 1–2 weeks during the first 3 growing seasons. Established trees require consistent moisture through the growing season and are intolerant of prolonged summer drought. Leaf margins scorch during dry periods exceeding 2–3 weeks without rain, particularly on exposed sites. Leaf blotch (Guignardia aesculi) may occur in humid climates but is typically less severe than on A. hippocastanum. Large leaves create dense shade, limiting understory growth. No regular fertilization is needed. Trees are intolerant of compacted soils and restricted root zones.Pruning
Prune during winter dormancy (November–February) to establish a central leader and remove dead or crossing branches. Structural pruning in the first 10–15 years develops a balanced scaffold framework. Lower branches can be removed to raise the canopy for clearance beneath the tree. Mature trees require minimal pruning beyond periodic dead wood removal.Pruning Schedule
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