The simplest seed starting calendar counts backward from your average last frost date. Onions and leeks go first, about 10-12 weeks before it. Peppers and eggplant follow at 8-10 weeks, tomatoes at 6-8 weeks, and cabbage-family crops and lettuce at 4-6 weeks. Fast growers like cucumbers, squash and melons need only 3-4 weeks indoors, or can be sown straight into warm soil after the frost date. Find your date, count back, and write the start dates on a calendar.
Step 1: Find your last frost date
Search your zip code plus "last frost date," or ask your county extension office. The date you get is an average, not a promise: there's still a real chance of frost after it, so warm-season crops usually go outside a week or two later. If you're unsure, plan around the date and keep an eye on the 10-day forecast at planting time.
Step 2: Use the chart
Weeks are counted from your average last frost date (LFD). Timing varies by variety, light and how warm you keep your seedlings, so treat the ranges as a guide and check each seed packet.
| Crop | Start indoors | Plant outside |
|---|---|---|
| Onions, leeks | 10-12 weeks before LFD | 2-4 weeks before LFD |
| Celery | 10-12 weeks before | 1-2 weeks after (cold nights can make it bolt) |
| Peppers | 8-10 weeks before | 1-2 weeks after, once nights stay above 50°F |
| Eggplant | 8-10 weeks before | 1-2 weeks after, once nights stay above 50°F |
| Parsley | 8-10 weeks before | 2-3 weeks before |
| Tomatoes | 6-8 weeks before | 1-2 weeks after |
| Broccoli, cabbage, cauliflower, kale | 4-6 weeks before | 2-4 weeks before |
| Lettuce | 4-6 weeks before (optional) | 2-4 weeks before, or direct sow |
| Basil | 4-6 weeks before | 1-2 weeks after |
| Annual flowers (zinnias, marigolds, cosmos) | 4-6 weeks before (optional) | After LFD, or direct sow |
| Cucumbers, squash, melons | 3-4 weeks before, in pots (optional) | 1-2 weeks after, in warm soil |
Crops to sow straight in the garden
| Crop | Direct sow |
|---|---|
| Peas, spinach | 4-6 weeks before LFD, as soon as the soil can be worked |
| Radishes, lettuce, arugula | 2-4 weeks before |
| Carrots, beets, turnips, chard | 2-4 weeks before |
| Beans, sweet corn | 1-2 weeks after, when soil is at least 60°F |
| Cucumbers, squash, pumpkins, melons | 1-2 weeks after, when soil is 65-70°F |
Root crops like carrots, beets and radishes don't transplant well, so always sow them where they'll grow.
Worked example: last frost April 15
- Early February: onions and leeks (around Feb 4).
- Mid-February: peppers, eggplant and parsley (Feb 4-18).
- Late February to early March: tomatoes (Feb 18 to Mar 4).
- Early March: peas and spinach direct sown outside; broccoli, cabbage, kale and lettuce started indoors (Mar 4-18).
- Late March to early April: transplant brassicas and lettuce; sow radishes, carrots and beets outside.
- Late April to early May: plant out tomatoes, peppers and basil; sow beans, corn, squash and cucumbers once the soil is warm.
For month-by-month lists, see what seeds to start indoors in February and what seeds to start in March.
Recommended seeds: Pepper Seed Starter Kit
Tips that make the calendar work
- Don't start too early. Seedlings that sit indoors too long get leggy and root-bound and often do worse than younger plants. When in doubt, start a week later.
- Give them real light. A sunny window usually isn't enough in late winter. A grow light a few inches above the seedlings for 14-16 hours a day makes the biggest difference.
- Warm the soil for peppers and eggplant. They sprout slowly in cool rooms; a heat mat helps.
- Harden off. Over about a week before transplanting, move seedlings outside for a little longer each day.
- Test old seed first. If you're using last year's packets, a quick germination test tells you whether to sow thicker. See our seed viability chart.
For trays, mix and lights, read how to start vegetable seeds indoors and seed starting mix vs potting soil.
Once you have your dates, see where everything goes in our first vegetable garden plan for a 4x8 raised bed.
Getting your seeds ready
Winter is the time to sort what you have and fill the gaps before February. If you're starting from scratch, a 35-variety kit covers most of the chart in one order: the Survival Seed Vault Kit includes onions, peppers, eggplant, tomatoes, cabbage-family crops, lettuce, beans, corn, squash and melons, and the Seed Safe adds leeks, artichoke and more greens. For tomatoes, the 8-variety tomato seed assortment gives you choices for slicing, paste and cherry. Not sure which kit fits? See the best heirloom seed kit for beginners, or browse our heirloom seed assortments.
Frequently asked questions
How many weeks before the last frost should I start tomatoes?
About 6-8 weeks before your last frost date, then plant them outside 1-2 weeks after it, once nights stay above 50°F.
What seeds should I start first?
Onions, leeks and celery, about 10-12 weeks before your last frost, followed by peppers and eggplant at 8-10 weeks.
Is it too late to start seeds indoors?
Usually not. If you missed the window, start anyway and plant out a little later, or direct sow fast crops like beans, squash and cucumbers once the soil warms. Late seedlings often catch up.
What if I don't know my frost date?
Your county extension office or a search for your zip code plus "last frost date" will give it. In the warmest southern zones, where frost is rare, many crops are started in fall and winter instead.
Do I need to start every crop indoors?
No. Beans, corn, peas, root crops and most squash do best sown directly in the garden. Starting indoors matters most for long-season crops like peppers, tomatoes, eggplant and onions.
Reviewed by Ryan, owner of Gardeners Basics, an heirloom seed company that ships from Spanish Fork, Utah.
