either heat or nutes probleams , is it too hot , what have you been feeding it and how much , or you havnt added nutes yet ,
It all started when i atomized/sparyed it with distilled water, within 24 hrs rust spots formed, i figured spraying was bad option, within another 24 hrs, it turned the color it has. Temps not bad at 24 degrees, the soil was donated by a friend who claim it be all organic with some amendments which he cant remember, so i have dug out 80 % of the soil that was in there and replaced with plain promix potting soil, yes the organic soil mighta been too hot/rich and foliar spraying, i think only time will tell ?
The color of the stems makes me think you have a serious PH issue. Is your friend experienced at making organic soil? Peat moss is acidic, which is why I use lime to raise the PH to get it back to neutral, he might not have done that or a million other things could have gone wrong. What I would do is transplant each of those into individual pots with the pro-mix you already have. Water after transplant, wait and watch them recover. During this time I would read, a lot. GL and have fun!