Grüner Schimmel Erdoberfläche

Hi buddy I would be looking 1stly into the difference in temperatures between day and night but u would see signs if mildew on ur plants. the nights are cold this time of year could cause the growth on ur soil, also how damp ur soil is could be down to overwatering? Or possibly simply the time of day ur watering from research if u water in the morning rather than night gives ur soil an opportunity to dry and also ur plants get all day whilst bathing under the sun/light to drink. My advice rough up the top layer of the soil being careful not to expose the roots and maybe raise the temps slightly temporarily being careful not to spike the temps to much as could cause shock. Out of curiosity what time are u watering and how far away are ur lights?