Damping Off
A soil fungus that topples healthy-looking seedlings overnight, collapsing them at the base.
🔍 How to spot it
Seedlings that were fine yesterday keel over, pinched and dark at the soil line, with a thin, water-soaked, thread-like stem base. Whole trays can go down in patches. Sometimes a fine white mould appears on the surface of damp compost.
💥 The damage it does
Several soil-borne fungi attack germinating seeds and young seedlings, rotting them at the base so they collapse and die. It strikes fast in cold, wet, airless conditions and can wipe out a whole sowing before the plants get going.
🧴 How to treat it
There is no cure once a seedling collapses - remove affected ones at once to slow the spread. Move the tray somewhere brighter and more airy, ease off the watering, and let the surface dry between drinks. Surviving seedlings often pull through with drier, better-ventilated care.
🛡️ How to prevent it
Sow in clean trays and fresh, sterile compost, and do not sow too thickly. Water from below, use tepid water, give good light and airflow, and avoid the cold, sodden, crowded conditions the fungi need.
🌿 Plants that get damping off
A seed-starting problem affecting almost any young seedling. These 3 profiled plants name it in their own troubleshooting notes:
Struggling to save a plant? The plant rescue guides walk through recovery step by step, and the problem solver works backwards from a symptom. This is general growing advice, not a diagnosis for a specific plant.