Step-by-Step Seed Planting
Fill containers with seed-starting mix
Use sterile seed-starting mix, not garden soil. Fill cell trays or small pots to 1/2 inch below the rim. Moisten thoroughly before planting.
Create planting holes
Use a pencil or your finger to make holes exactly 1/4 inch (6mm) deep. Space 2 inches apart if planting multiple seeds per container.
Place seeds and cover
Drop 2-3 seeds per cell (you'll thin later). Cover with 1/4 inch of seed-starting mix. Gently press surface to ensure seed-to-soil contact.
Provide warmth and moisture
Cover with a humidity dome or plastic wrap. Place on a heat mat or warm location (70-80°F). Keep soil consistently moist but not waterlogged.
Remove cover when seedlings emerge
Once you see green sprouts, remove the humidity cover immediately and provide bright light (14-16 hours daily).
Optimal Conditions for Germination
| Factor | Optimal Range |
|---|---|
| Planting Depth | 1/4 inch (6mm) |
| Soil Temperature | 70-80°F (21-27°C) |
| Germination Time | 5-10 days |
| Soil Moisture | Consistently moist, not soggy |
| Light (before germination) | Not required (darkness OK) |
| Light (after germination) | 14-16 hours daily |
Common Seed Starting Mistakes
Planting Too Deep
Seeds planted deeper than 1/2 inch may rot or produce weak seedlings. Stick to 1/4 inch depth.
Cold Soil
Soil below 60°F dramatically slows germination. Use a heat mat to maintain 70-80°F.
Letting Soil Dry Out
Seeds need consistent moisture to germinate. Check daily and mist if surface begins to dry.
Using Garden Soil
Garden soil compacts, drains poorly, and may contain diseases. Always use sterile seed-starting mix.
Frequently Asked Questions
How deep should I plant tomato seeds?
Plant tomato seeds exactly 1/4 inch (6mm) deep in moist seed-starting mix. This depth provides enough coverage to keep seeds moist while being shallow enough for seedlings to push through easily. Planting too deep is the most common cause of poor germination.
Can I plant tomato seeds too deep?
Yes, planting deeper than 1/2 inch significantly reduces germination rates. The seedling uses energy pushing through soil instead of developing leaves. Seeds planted too deep may rot before germinating or produce weak, stretched seedlings.
Do tomato seeds need light to germinate?
No, tomato seeds germinate in darkness and don't need light until after they sprout. Cover seeds with soil as directed. Once seedlings emerge, immediately provide 14-16 hours of bright light to prevent leggy growth.
How long do tomato seeds take to germinate?
Tomato seeds germinate in 5-10 days at optimal temperatures (70-80°F / 21-27°C). Cooler temperatures slow germination to 2-3 weeks. Seeds older than 4 years may have reduced germination rates.
Related Questions
Complete Tomato Growing Guide
From seeds to harvest - learn everything about growing tomatoes in containers.