About PlantWhenNow

PlantWhenNow is a free planting calendar tool that tells you when to start seeds, transplant, and harvest based on your ZIP code.

The dates come from two government data sources:

• The USDA Plant Hardiness Zone Map, which divides the U.S. into growing zones based on average annual minimum winter temperatures
• NOAA climate records, which provide historical frost date averages by region

We cross-reference these datasets with planting recommendations from university cooperative extension programs to generate schedules for 30+ vegetables and herbs.

Why we built this

Most planting calendars online are either too generic ("plant tomatoes in spring") or locked behind paywalls. We wanted something that gives you actual dates based on where you live, without asking for an account or a credit card.

How it works

You enter your ZIP code. We map it to your USDA hardiness zone, pull the average frost dates for that zone, and calculate planting windows for each crop. Everything runs in your browser. We do not send your ZIP code to any server.

Limitations

These are estimates based on averages. Your yard might be in a frost pocket, or protected by a south-facing wall, or at a different elevation than the zone average. Local conditions matter. When in doubt, check with your county extension office.

Contact

Suggestions or corrections? Email hello@plantwhennow.com.