Japanese Maple
Acer palmatum
Sapindaceae · broadleaf deciduous tree · introduced
Last updated
This is the tree that the Puget Sound lowlands do better than almost anywhere else in the country. Our maritime climate is close enough to the species' native mountain forests in Japan that they grow here with an ease that gardeners in warmer, drier parts of the country would find infuriating. The main thing people get wrong is siting: full afternoon sun in July will scorch the fine foliage, especially dissected-leaf varieties. Morning sun with dappled afternoon shade is the move for most yards in this region. Most lowland soils are fine as long as drainage is real, not aspirational. Of the nineteen diseases on this profile, Verticillium wilt is the one that actually matters. It's soilborne, it persists indefinitely, and there's no chemical fix. Most of the rest are cosmetic. If your Japanese maple looks rough in August, it's almost certainly a siting problem, not a disease.
— Chris Welch, ISA Certified Arborist
A deciduous small tree or large shrub, typically 10 to 25 feet in cultivation, with layered branching and a rounded canopy that broadens with age. The species is extraordinarily variable: leaf forms range from shallowly lobed (the straight species) to deeply dissected laceleaf types, and foliage color spans green, burgundy, and variegated selections. Fall color runs from gold through orange to scarlet depending on the cultivar. The genus carries one of the longest susceptibility lists in the knowledge base, nineteen documented diseases and fifteen pests, though most are cosmetic rather than structural.
No tree species has been more variable in cultivation. Over seventy cultivars circulate in the regional nursery trade, spanning upright forms like 'Bloodgood' and 'Sango Kaku', laceleaf dissectums like 'Crimson Queen' and 'Tamukeyama', columnar selections like 'Twombly's Red Sentinel' and 'Tsukasa Silhouette', and true dwarfs under six feet. The range of habit, color, and leaf form means there is a Japanese maple for nearly any garden scale. Across all cultivars, site selection matters more than variety selection: part shade with morning sun produces the best foliage, and well-drained soil is essential. Verticillium wilt is the primary threat to all maples; the soilborne fungus persists indefinitely and there is no chemical control.
Quick Facts
Phenological Calendar
| Stage | Typical Window |
|---|---|
| Bud break BBCH 07 | Mar 15-Apr 1 |