About GrowDate Atlas

GrowDate Atlas exists because most "when to plant" pages answer with a hardiness zone, and a hardiness zone is the wrong number. It describes the coldest winter night, not the last spring frost. This site uses the frost dates NOAA already publishes for thousands of stations and applies planting rules from university extension guides, with every input shown.

Author

The GrowDate Atlas team. GrowDate Atlas is built and maintained by a small independent team. We compile frost dates from NOAA and crop timing rules from university extension services, show the source and retrieval date for every figure, and publish the assumptions behind any calculation on the methodology page. We are not affiliated with, and not endorsed by, any of the organisations whose published data appears here.

Data and method

See the methodology page for sources, retrieval dates and the one assumption that is ours.