SowByZip is a small independent website with free planning tools for home vegetable and flower gardeners in the United States: frost dates by ZIP code, a sow-this-week list, a planting calendar, a seed-starting calculator, a raised-bed soil calculator and a private garden journal.
Data
Frost probabilities come from NOAA’s 1991–2020 U.S. Climate Normals and ZIP locations from the U.S. Census Bureau, both public-domain federal data. Crop timings follow common U.S. Cooperative Extension guidance. See data sources for details. We are not affiliated with NOAA, the Census Bureau or any university.
How it is made and funded
The site is built and maintained with the help of automated software tools, and the calculators are covered by automated tests. It is free to use and may show advertising to cover costs. Advertisers have no influence on the data or advice.
Not professional advice
The tools give general guidance based on long-term averages. Local conditions, weather and varieties differ; check your local forecast and your state’s Cooperative Extension service for region-specific advice.
Contact
Corrections and suggestions: [email protected].