What is the 'AHS Plant Heat Zone Map'?

What is the 'AHS Plant Heat Zone Map'?

Tracy DiSabato-Aust (Garden Designer and Author) gives expert video advice on: What is the 'USDA Hardiness Zone Map'?; What is the 'AHS Plant Heat Zone Map'?; What is the 'Sunset zone map'? and more...

The plant heat zone map was established by the American Hort Society. It tells us the number of days that an area would experience temperatures above 86 degrees. This is just as important as average low temperatures, because many plants are intolerant of high heat or particularly high humidity.