I don't know how many of the "Super Databases" have hardiness zone criteria but I've found these 3 plus the standard one.
General Plant Info: "Minimum cold hardiness"
Heuchera: "USDA Zone Range:"
Iris: "Hardiness (zone temps are in Farenheit):"
Clematis: "Growing Zones"
Is there any benefit in labeling the 3 plant specific ones the same thing?
