Symptom
Seedlings collapsing
Seedlings are soft and small, so one night of slugs or cutworms, or a spell of wet cold compost, can finish a sowing. The stem base and the soil around it tell you which.
Look at the stem base. Pinched and dark means damping off; cut through means cutworms; grazed with slime means slugs.
Likely causes
Ordered from the usual answer to the less likely one. Each links to the full problem.
Recorded on Bell peppers
-
Pest Common
Cutworms
Stems cut at soil level; caterpillar in the soil. -
Damage Possible
Transplant shock
Wilting just after planting out.
Less likely on Bell peppers
-
Fungal disease Common
Damping off
Pinched, dark stem at soil level; patches of collapse. -
Pest Common
Slugs and snails
Seedlings grazed away with slime trails. -
Pest Possible
Fungus gnats
Indoor seedlings failing; larvae in compost. -
Pest Less likely
Rabbits, deer and other mammals
Bitten off, with droppings nearby.