Keimlinge sterben, immer gleiche Symptome, unterschiedliche Erde, erste Erde ph zu hoch, zweite Erde mit passendem ph trzd stirbt keimling

Sometimes it can be hard to get the watering right for a seedling in a big pot, it's easier in a small pot. Your either drowning the seedling or the soil isn't damp enough. I usually start in a big pot but water the soil thoroughly a few days before the seed goes into the soil. So example 12L pot soaked until runoff, usually takes 3-5L of water, I then know there is no dry spots in the medium. Then I usually don't need to water again for a week. I found when I didn't do it that way it would be hit and miss if a seed made it or not. Your welcome to check out some of my newer diaries which are very detailed on every process I do.

Seedlings that small are very sensitive to changing conditions. The root is at this point not much bigger than the seedling and its restricted to finding water in that top inch of soil. Light/ambient heat/evaporation from the grow light itself can very rapidly dry out the top couple inches. During the long 18 hour days, most likely having a very hard time with that. Use a aluminum burner liner from dollar store to create a temporary artificial mulch and help deflect some of the heat thats chewing up the water in and around the seedling. Alot of people like to use a dome to increase humidity which slows the rate thay water is released from the seedling, but a dome will simultaneously stifle gas exchange.