

- Mar 1, 2020
Would That It Were That Simple
The USDA Plant Hardiness Zone Map was originally compiled at the Arnold Arboretum, first published in 1938 and most recently updated (for only the second time) in 2012. * The previous update was in 1990. The map can be useful in helping to decide whether or not to place a particular species in the landscape as a potential perennial, but temperature is just one limiting factor. Moreover, the temperatures used in creating the zone boundaries (the thermoclines) of the USDA ma