Seeds Sprouted Then Died? It’s Damping Off
Damping off is a fungal disease that kills seedlings at the soil line. It’s caused by too much moisture and not enough airflow — both fixable.
How to Confirm
- Stem is thin and pinched at soil line
- Seedling falls over without support
- Soil surface is wet or has white fuzz
- Multiple seedlings affected at once
The 3 Causes
- Overwatering — wet soil grows fungus
- Poor airflow — stagnant air
- Contaminated soil — reused soil or dirty pots
How to Stop It
Immediate actions:
- Remove and discard affected seedlings (do not compost)
- Stop watering. Let soil surface dry.
- Add a small fan on low, 6+ hours/day
- Sprinkle cinnamon on soil surface
If it keeps happening:
- Switch to bottom watering
- Use fresh seed-starting mix
- Sterilize pots with 10% bleach solution
Prevention
| Factor | What to Do |
|---|---|
| Water | Bottom water only |
| Airflow | Small fan on low, 6+ hours/day |
| Soil | Fresh mix every time |
| Spacing | Thin early |
| Temperature | 65-70°F, not warmer |
Common Questions
Can a collapsed seedling recover? No. Once the stem is pinched, it’s dead.
Will it spread to other seedlings? Yes. Remove affected ones immediately.
Does cinnamon really work? It has antifungal properties. Not a cure, but helps prevent spread.
Is damping off the same as root rot? Related, but different.
Can I reuse the soil? No. Discard it.
Why does it happen every time I start seeds? Probably overwatering + no airflow.