Contents
Calculator
Use this seed starting calculator to determine the best time to start your crops based on your final frost date.
To find your last frost date, visit the Almanac and calculate your frost date based on your location.
Want to learn more about seed starting? Get instant access to our course on seed starting or read our article: The Ultimate Guide To Starting Vegetable Seeds Indoors

Seed Starting Chart
Crop | Weeks to Start Before Last Frost Date |
---|---|
Tomatoes | 6-8 weeks |
Peppers | 8-10 weeks |
Lettuce | 4-6 weeks |
Broccoli | 6-8 weeks |
Pumpkins | 2-4 weeks |
Cucumbers | 3-4 weeks |
Eggplant | 8-10 weeks |
Beans | 3-4 weeks |
Kale | 6-8 weeks |
Cabbage | 6-8 weeks |
Spinach | 4-6 weeks |
Cauliflower | 6-8 weeks |
Swiss Chard | 4-6 weeks |
Celery | 10-12 weeks |
Onions | 8-10 weeks |
Tomatillo | 6-8 weeks |
Artichoke | 8-10 weeks |
Leeks | 8-10 weeks |
Brussels Sprouts | 6-8 weeks |
Parsley | 6-8 weeks |
This table can be used as general guideline for how early to start their seeds based on the crop you are planting. You can use this data to provide valuable advice for each type of crop.
Seed Starting Basics
Starting seeds indoors is a great way to give your plants a head start, especially for crops that need a longer growing season. The key to successful seed starting is timing. By planting your seeds at the right time, you can ensure they are strong and ready for transplanting once the weather warms up and the last frost has passed. Here’s how you can get started:
- Know Your Planting Zone: The first step in determining when to start your seeds indoors is knowing your planting zone, or your area’s last frost date. This date is crucial as it marks when it’s safe to move your seedlings outside. You can find your area’s last frost date based on your USDA hardiness zone or local climate data.
- Understand Crop Needs: Different crops need different amounts of time to grow from seed to transplant. Some plants, like tomatoes and peppers, require a longer indoor growing period, while others, like lettuce and beans, need less time. The table above shows the recommended number of weeks to start various crops indoors before your last frost date.
- Prepare Your Containers and Soil: Start your seeds in trays or pots filled with seed-starting mix. This mix is designed to provide the right balance of drainage and moisture retention, giving your seeds the best chance to germinate. Be sure to use clean, sterilized containers to avoid any disease issues.
- Provide Proper Light and Heat: Most seeds require warmth to germinate. A seedling heat mat can help maintain the optimal soil temperature. Once your seeds have germinated, they need a lot of light to grow strong. If natural sunlight is insufficient, consider using grow lights to keep your plants healthy.
- Transplanting: Once your seedlings are ready and the last frost has passed, it’s time to transplant them into your garden. Before doing so, “harden them off” by gradually acclimating them to outdoor conditions. This can be done by placing them outside for a few hours each day, increasing the exposure to sunlight and wind over the course of a week.
By following these steps and using our seed starting calculator, you can successfully start seeds indoors and ensure your plants are ready for transplanting when the time is right.