Ask-a-Dave's-Gardener: thyme leaves turning red, 0 by microgreener

microgreener wrote:
Hello, I'm having a problem with my thyme seedlings turning red. I planted in just topsoil, it doesn't have very much nutriitional value. They did fine for the first 2 weeks then turned red and stopped growing, do I need to fertilize it? I'm growing as a microgreen so I'd rather not. It's German winter thyme from johnnys selected seeds. Temperature maintains 75-70 t5 growing lights 14 hours a day. All other plants have done fine only variable is the soil. It is possible I'm over watering, I never let the soil completely dry out, but from my research thyme turns yellow and brown from overwatering. I have other trays growing that are still green but they are in their first week. Planted in a mix of topsoil and compost. Thanks for your help!!!!