Seed Starting Date Calculator
By Crop Type
Calculate seed starting date based on crop and last frost date
Custom Weeks Before Frost
Enter custom weeks before last frost for any crop
Formula
Start Date = Last Frost Date - (Weeks Before Frost × 7 days) | Transplant Date = Last Frost Date + 7 days (after hardening off)
Frequently Asked Questions
When should I start tomato seeds indoors?
Start tomato seeds indoors 6-8 weeks before your last frost date. For most zones in the US, this means starting in February to April depending on your location. Tomatoes need warm soil (70-85°F) to germinate.
How do I find my last frost date?
Check the USDA Plant Hardiness Zone Map or contact your local extension office. Common last frost dates: Zone 3-4 (May 15-30), Zone 5-6 (April 15-May 15), Zone 7-8 (March 15-April 15), Zone 9-10 (February 1-March 1).
What supplies do I need to start seeds indoors?
You need seed starting mix (not regular potting soil), seed trays or cell packs, a humidity dome, grow lights or a sunny south-facing window, a heat mat (optional but helpful), and a spray bottle for watering.
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