Data studies
Our own analyses of the public records behind garden planning. Each study explains its method, links its sources and lets you download the table; garden writers and educators are welcome to cite it with a link.
Studies
- Who Moved Hardiness Zones: 2012 vs 2023 USDA Maps by StateHow many ZIP codes, and how many people, changed USDA plant hardiness half zone between the 2012 and 2023 maps, state by state, with what USDA says caused the shifts and a downloadable table.
- Frost Dates and Growing Season by StateTypical last spring frost, first fall frost and frost-free days for every state, from 7,000+ NOAA weather stations, with the extremes and a downloadable table.