When to Start Seeds Indoors by Zone
A zone-by-zone guide to starting seeds indoors. Covers timing for tomatoes, peppers, herbs, and more based on your USDA hardiness zone.
February 28, 2026
The formula: Find your last frost date. Count backwards. Peppers need 8-10 weeks, tomatoes 6-8 weeks, quick growers 3-4 weeks.
Weeks Before Last Frost
| Crop | Start Indoors |
|---|---|
| Peppers, eggplant | 8-10 weeks before |
| Tomatoes, broccoli, cabbage | 6-8 weeks before |
| Lettuce, kale, chard | 4-6 weeks before |
| Cucumbers, squash, melons | 3-4 weeks before |
| Basil, marigolds, zinnias | 2-4 weeks before |
Last Frost Dates by Zone
| Zone | Avg Last Frost | Avg First Frost |
|---|---|---|
| 3 | May 15 | Sep 15 |
| 4 | May 1 | Oct 1 |
| 5 | Apr 15 | Oct 15 |
| 6 | Apr 1 | Oct 30 |
| 7 | Mar 15 | Nov 15 |
| 8 | Feb 28 | Nov 30 |
| 9 | Feb 15 | Dec 15 |
| 10 | Rarely frosts | Rarely frosts |
Check your local extension office for more precise dates.
Example Schedule: Zone 5 (Last frost ~April 15)
| Crop | Start Indoors | Transplant Out |
|---|---|---|
| Peppers | Feb 1-15 | May 1 |
| Tomatoes | Feb 15 - Mar 1 | May 1 |
| Broccoli/Cabbage | Feb 15 - Mar 1 | Apr 15 |
| Lettuce/Kale | Mar 1-15 | Apr 15 |
| Basil | Mar 15 - Apr 1 | May 1 |
| Cucumbers/Squash | Apr 1 | May 1 |
Example Schedule: Zone 7 (Last frost ~March 15)
| Crop | Start Indoors | Transplant Out |
|---|---|---|
| Peppers | Jan 1-15 | Mar 30 |
| Tomatoes | Jan 15 - Feb 1 | Mar 30 |
| Broccoli/Cabbage | Jan 15 - Feb 1 | Mar 15 |
| Lettuce/Kale | Feb 1-15 | Mar 15 |
| Basil | Feb 15 - Mar 1 | Mar 30 |
| Cucumbers/Squash | Mar 1 | Mar 30 |
What You Need
- Seed starting mix (not garden soil — too dense, may carry pathogens)
- Trays or cell packs with drainage holes
- Grow lights or a very sunny south-facing window
- Heat mat (optional, helps peppers/tomatoes germinate faster)
- Labels (you will forget what's what)
Three Tips That Matter Most
1. Light is everything. Leggy, weak seedlings = not enough light. A sunny window usually isn't sufficient. A basic grow light 2-3 inches above seedlings, 14-16 hours/day, makes a huge difference.
2. Bottom water. Place trays in a shallow pan of water instead of watering from above. Gentler and prevents damping off (a fungal disease that kills seedlings at the soil line).
3. Harden off. Indoor seedlings need 7-10 days to adjust to outdoors. Start with a few hours in shade, gradually increase sun and time. Skip this and they'll sunburn.
Just Direct Sow These
Some crops do better planted straight in the garden:
- Root vegetables (carrots, beets, radishes, turnips) — don't transplant well
- Beans and peas — fast growers, sensitive roots
- Corn — needs space, direct sow after frost
- Spinach — prefers cool soil, sow early spring