I sowed tomatoes. Some have sprouted, but some have a green alkaline substance on the soil. Is it safe to keep them?
They should be fine. That green mold *could* be a result of over-watering.
Check out this thread and see if it is helpful to you.
[Green mold on soil[(https://www.houzz.com/discussions/green-fungus-mold-on-soil-dsvw-vd~1578512)