GardenMath

🌱 Seed Starting Helper

Diagnose common seed starting problems and get personalized tips for temperature, light, humidity, and container setup.

Get Seed Starting Tips

Enter your current conditions to get a personalized diagnosis and recommendations.

Set your conditions and click Get Suggestions.

© 2025 GardenMath. Seed starting results vary by variety, location, and conditions. This page does not store personal data.

Common Seed Starting Problems

Damping off is a fungal disease that causes seedlings to collapse at the soil line. Prevent it with sterile seed starting mix, good drainage, and airflow. Avoid overwatering — the mix should be moist but never soggy.

Leggy seedlings stretch toward the light and become weak and spindly. The fix is more light (14–16 hours under grow lights, with lights just 2–3 inches above seedlings) and a gentle fan to strengthen stems.

Poor germination is often a temperature problem. Most seeds germinate best at 65–80°F. Peppers in particular need soil temperatures of 80–85°F — a heat mat makes a significant difference.

When to Start Seeds Indoors

Count backward from your last frost date. Tomatoes and peppers need 6–8 weeks indoors before transplanting. Lettuce and basil need 4–6 weeks. Check your local extension service for last frost dates by zip code.