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Acer shirasawanum 'Autumn Moon'
Autumn Moon Maple
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Overview
Acer shirasawanum 'Autumn Moon' is a deciduous shrub or small tree reaching 8–12 feet (2.4–3.7 m) tall with a spread of 6–10 feet (1.8–3 m) over 10–15 years, forming a rounded to vase-shaped crown. Leaves are nine- to eleven-lobed, 2.5–4 inches (6–10 cm) wide, with pointed lobes and finely serrated margins, rounded in overall outline. Spring foliage emerges apricot-orange to orange-yellow, transitioning to yellow-green by midsummer, then to orange-red in fall — the spring apricot-orange flush persisting 3–5 weeks. This spring color is more orange-tinted than the golden-yellow of A. shirasawanum 'Aureum' and is the primary distinguishing feature of the cultivar. Small reddish-purple flowers appear in pendant corymbs in April–May. Samaras, 0.75–1 inch (2–2.5 cm) long, ripen in September–October. Growth rate is slow, 4–6 inches (10–15 cm) per year. Like all A. shirasawanum cultivars, leaf scorch occurs with afternoon sun above 80°F (27°C).
Native Range
Acer shirasawanum is native to the mountains of Japan, occurring in cool, moist mixed forests on Honshu at elevations of 3,000–6,600 feet (900–2,000 m). The 'Autumn Moon' cultivar was selected through horticultural breeding and does not occur in wild populations.Suggested Uses
Planted as a specimen in Japanese-style gardens, courtyard gardens, and mixed shrub borders at 7–9 foot (2.1–2.7 m) spacing. The apricot-orange spring foliage and orange-red fall color are the primary seasonal features. Suitable for containers of at least 15 gallons (57 L) in sheltered positions. Not suited to full afternoon sun in warm climates, alkaline soils, or exposed windy sites.How to Identify
Appearance
Size & Dimensions
Height8' - 12'
Width/Spread6' - 10'
Reaches mature size in approximately 12 years
Bloom Information
Small reddish-purple flowers appear in pendant corymbs in April–May as new leaves emerge. Individual flowers are 0.3–0.4 inch (8–10 mm) across. Samaras, 0.75–1 inch (2–2.5 cm) long, ripen in September–October.Detailed Descriptions
Foliage Description
apricot-orange to orange-yellow in spring, transitioning to yellow-green in summer; orange-red in fallGrowing Conditions
Sun Requirements
Requires 2-6 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
Care & Maintenance
Care Guide
Plant in moist, well-drained, humus-rich soil with a pH of 5.5–6.5 in partial shade — morning sun with afternoon shade is standard in most climates. Afternoon shade is required where summer temperatures exceed 80°F (27°C) to prevent scorch on the colored leaf tissue. Water weekly during the first two growing seasons and through summer dry spells. 'Autumn Moon' tolerates more sun than 'Aureum' without scorching and performs in a slightly wider range of summer temperatures, though it is not suited to hot-summer climates above zone 7b without shade. No routine fertilization is required in humus-rich soils.Pruning
No routine pruning is required. The rounded to vase-shaped crown is self-maintaining. Prune in late spring to early summer (May–June) after leaf-out if shaping is needed. Remove dead or crossing branches. Avoid late summer or fall pruning.Pruning Schedule
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late spring
Maintenance Level
lowContainer Growing
✓ Suitable for container growing
Minimum container size: 15 gallons
⚠️ Toxicity Warning
Non-toxicBotanical Flashcard
