Seed Starting Date Calculator
Timing is everything when starting seeds indoors. Enter your area's last frost date and how many weeks before frost your seeds need, and this calculator gives you exact dates for sowing, hardening off, and transplanting outdoors.
How it works:
- Start seeds indoors = Last frost date minus the weeks listed on your seed packet
- Begin hardening off = Transplant date minus 7-14 days
- Transplant outdoors = Last frost date plus any extra waiting days
Weeks before last frost to start common crops:
- Tomatoes: 6-8 weeks
- Peppers and eggplant: 8-10 weeks
- Lettuce and greens: 4-6 weeks
- Basil and herbs: 6-8 weeks
- Broccoli and cabbage: 6-8 weeks
- Cucumbers and squash: 3-4 weeks
- Flowers (petunias, zinnias): 6-8 weeks
What is hardening off? Seedlings grown indoors need to be gradually exposed to outdoor conditions (sun, wind, temperature swings) over 7-14 days. Start with a few hours of shade and work up to full sun. This prevents transplant shock.
Finding your last frost date: Search your zip code or city at the USDA Plant Hardiness Zone map or your state's cooperative extension website. The "average last frost" date means there is roughly a 50% chance of frost after that date.