Damping Off: Why Seedlings Fall Over and Die
On this page
Here today, flat tomorrow
Seedlings thin and darken at the base and topple, often spreading outward across a tray; seeds may also rot before they emerge. The culprits are Pythium, Rhizoctonia, Fusarium and Phytophthora.
What invites it
Wet compost, high humidity, poor air circulation and crowded sowings favour it. A tray sown thickly, covered and kept wet is the perfect setting.
Start clean
Use fresh, sterile seed compost, never garden soil, and clean trays and pots.
Sow thin, let it breathe
Sow thinly, take covers off once seeds have germinated, and keep air moving. Modules with one seedling each are easier to manage than a crowded tray.
Related problems: seeds not germinating, overwatering, why plants are not growing. Or go back to all garden problems.
Damping off questions
Can I save seedlings that have fallen over?
No; resow in fresh compost and clean trays.
Can I reuse the compost?
No. Use fresh sterile compost for seed sowing.
Regional notes
The problem is the same on both sides of the Atlantic; local advice and timing differ. Trusted local guides for this page:
- UK: RHS: Damping off. Timing in your area: the UK vegetable planting calendar.
- USA: Penn State Extension: Damping off; Utah State University Extension: Damping-off (fact sheet). Timing in your area: the USA vegetable planting calendar.
- Canada: University of Saskatchewan, Gardening at USask: Damping off. Timing in your area: the Canada vegetable planting calendar.
More problems: all garden problems.
Sources and further reading
- RHS: Damping off
- Penn State Extension: Damping off
- Utah State University Extension: Damping-off (fact sheet)
- University of Saskatchewan, Gardening at USask: Damping off
Facts on this page are summarised in our own words from the pages above; each is supported by at least two of them, or by one plus well-established growing science (noted in our research file). Every source was opened and checked on 23 October 2026.
Keep a garden record
Most problems come back to the same beds in the same weeks. A simple record of what grew where, and when trouble started, lets you get ahead of it next year. Sketch your beds in the free Vegetable Garden Layout Planner Tool, and keep sowing dates, problems and harvests in the Global Vegetable Garden Planner (printable PDF). Every crop we cover is in the vegetable growing guides.
Last reviewed:
Fix The Cause, Then Plan The Next Crop
Troubleshooting works best when you improve the growing conditions and record what changed for the next season.
Keep going
Plan the next step
Use the printable SoilCommander planner for your region to turn this guide into sowing dates, bed layouts and weekly garden tasks.