All my seedlings seem to grow spindly and keel over. Is it too much watering, perhaps?
Seedlings are commonly affected by a soil-borne fungal infection called “damping off”. Symptoms include seedlings which failing to sprout, or withering away at soil level and collapsing from the base. Unfortunately affected seedlings can’t be saved, so dispose of any unhealthy seedlings and soil and start again. Damping off occurs when seedlings are overcrowded and/or over-watered. Keep your seedlings in a warm, airy place, don’t over-water them (keep the soil moist, but not soaking wet) and pick out some seedlings (this is called thinning) if they’re packed in too tightly.