Norway Maple ‘Crimson King’ · Acer platanoides ‘Crimson King’

'Crimson King' is a purple-foliage selection of Acer platanoides, holding deep maroon to near-black leaf colour from leafout in April through to autumn, when foliage shifts to bronze and red tones before drop. The crown is dense, broadly rounded, and symmetrical, reaching roughly 15 to 20 metres in height and 10 to 12 metres in spread at maturity under continental European conditions. Yellow-green corymbs open in early spring before the foliage emerges, briefly conspicuous before the dark canopy fills in.

Climate envelope follows the parent species and is broad. Acer platanoides is native from Scandinavia and the Baltic states south to the Balkans and east into the Caucasus, and the cultivar inherits that cold hardiness: reliable across USDA zones 4 to 7, withstanding winter minima around minus 30 degrees Celsius without dieback. Northern and eastern performance within Europe is essentially unbounded; the practical limit is to the south, where prolonged maxima above 35 degrees Celsius and summer drought below roughly 500 millimetres annual rainfall produce leaf scorch, accentuated on this dark-foliage cultivar.

Site tolerance reads as the European urban canon expects of Norway maple. The cultivar accepts clay, sandy, acidic, and alkaline soils provided drainage is reasonable, tolerates compaction and urban pollution, and performs in full sun or partial shade. It sits naturally in the specification space alongside Tilia cordata and Quercus robur as a cold-temperate avenue and parkland tree, offering a dark-foliage counterpoint to the green-canopy default of those staples.

Two limits should sit on the project file. The root system is shallow and competitive, which makes the cultivar unsuitable beside turf, sensitive paving, or close underplanting; allow adequate tree-pit volume and offset from kerbs and services. Verticillium wilt is the principal disease pressure across the genus, with no in-field treatment once established, so siting on well-drained ground and avoiding waterlogged or repeatedly stressed positions is the practical safeguard.