Unique Features: The Norway maple was introduced here in the 1700’s and adapted well enough to become invasive in the eastern U.S.  So far that’s not a problem in Colorado. They grow at a moderate rate, have strong wood, and the deep green leaves are large and cast a dense shade. They do have shallow roots that can lift sidewalks, and they can be picky about water. The Royal Red grows more slowly the other Norway maples, but has better disease resistance and is a little less prone to ‘frost cracking’.  Maples ‘wake up’ as early as February, and necessitate an increase in winter watering at this time. The Norway maples are less affected by soil pH, but are somewhat intolerant of poorly drained soils so it is recommended to elevate the top of the root ball above grade level by several inches.