A white looking film begins to appear on the surface of soil?

Every time I’ve planted my seeds they grow just fine but eventually a film of I’m guessing could be mold appears? It’s a slight white almost blue but more white film appears. There’s tiny Nats too. If I change out the soil I’m positive it will just return how do I prevent it?

throw away all containers and really clean your grow space . get new everything, soil, container’s, ect

This sounds like you are keeping the soil too wet. Mold on the surface and excessive gnats are often the signs of over watering.


I have to say two things about your answer.

High humidity meant the soil wasn’t drying out fast enough, you might not have been watering too often, but this still fits the definition of over watered.

And absolutely the hard water would cause the mineral build up in the soil that caused your soil to become so hard, and “crusty” with mineralization.

In the above descriptions, I don’t necessarily think you are experiencing the same “white film” either. Iron joe’s, with the “blue” tint does sound more like a “grey” mold, and maybe yours was more of a mineral crusting on the surface, which would normally only be chalky white.

But you certainly bring up good things for Joe to think about and look into, and of course we could do to hear back from Joe with any further details or information that could help us lock in which ever one of these might be more similar to his situation.

Thanks for helping out @pigSquishy, you obviously have had lots of experience and your comments and information are more than welcomed.

happy growing,


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And I don’t think everything needs be thrown away at all. Cleaning the containers with bleach should be more than enough. And just be sure the new sterilized soil is not staying too wet.


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