π± Seed Starting Date Calculator
Enter your last spring frost date and indoor sow weeks to get the indoor sow date, hardening-off start, and outdoor transplant date. Includes common vegetable presets and a fall-crop planner.
β Spring Sowing Plan
β‘ Fall Crop Plan (optional)
How It Works
This tool assumes a safe transplant date equals your last spring frost date:
Hardening-off start = transplant β hardening days
Transplant date = last frost date
Fall: fall transplant = first fall frost β days to harvest
Fall sow date = fall transplant β sow weeks Γ 7
Tip: microclimate, elevation, and variety affect the real safe transplant window. Combine with local guidance and weather forecasts. Hardening off significantly improves seedling survival.
FAQ
Why start seeds indoors early?
Long-season crops like tomato and pepper can't finish outdoors if sown after frost. Starting indoors grows sturdy seedlings in warmth; once frost risk passes you transplant them, extending the growing season and boosting yield.
What does "sow weeks" mean?
Indoor care time from sowing to outdoor transplant. Tomato needs about 5β7 weeks; pepper and eggplant need 7β9 weeks because they germinate and grow slowly. Presets fill recommended values per crop.
What is hardening off?
Hardening off gradually acclimates seedlings to outdoor sun, wind, and temperature swings over 7β14 days before transplant. Moving tender indoor seedlings outside directly causes wilting or death. Hardening-off start = transplant date minus hardening days.
How is the fall crop plan calculated?
To harvest before the first fall frost, the crop must finish its transplant-to-harvest days first. The tool subtracts those days from the first fall frost to get the fall transplant date, then subtracts sow weeks for the fall indoor sow date β ideal for cool crops like lettuce and broccoli.