Draft 2003 USDA Hardiness Map - new Tropical Zones
To all of you current Hawaiian residents:
Do check out the draft of the updated 2003 USDA Hardiness Zone map that is currently posted on the AHS (American Horticultural Society) website here. It is based on data from 1987 - 2001. Once it has been peer-reviewed and approved, this map will replace the current USDA Hardiness map which was last updated in 1990 and that used data from 1974 - 1986. The actual map can be downloaded from a separate link on that site. The map is large and will take some time to download, particularly on a dialup (aout 5 minutes on broadband and up to 30 minutes on dialup). The map is viewable via Adobe Acrobat and there is a "Zoom" feature from Acrobat so that you can point it to your state and zoom in to county level to see the new Zone divisions.
One of the major changes that directly impacts Hawai'i is that 3 additional Hardiness Zones (for a total of 4 "Tropical" Zones) have been created - Zones 12 - 14, so that the island chain is no longer lumped into a generic "Zone 11" (frost free). I am sure that you all know that there are many variations in climate within and among the various islands depending on elevation and position relative to the tradewinds and along the coasts, and that impacts your winter temperatures.
The new Tropical Zone divisions now describe avg. winter min. temps in the same type of 10 degree ranges that the lower Zones use and will be the following: 40Â° F - 50Â° F (Zone 11), 50Â° F - 60Â° F (Zone 12), 60Â° F - 70Â° F (Zone 13), 70Â° F+ (Zone 14). From my following certain threads on the Tropicals Forum, I understand that there are a number of temperature sensitive tropicals that can suffer with temps below 60Â° F, yet the old USDA Hardiness maps didn't subdivide to account for this. Thus hopefully this will help in your selection of shrubs and perenials and how successful they can be in your climates (of course knowing there are always microclimates and other factors that will impact plant health).
I would be interested to hear how you all feel about this! :-)