By the color of your medium and slow Growth, you are over watering. Pretty much the most common mistake and seed killer. Not saying this caused your issues, but you may want to add some airflow or back off the frequency or amounts of water. Good luck
I am absolutely not over watering, I underexpose my images, and properly expose my subject, yes the soil looks dark, it should. Many here whom shoot with flash or use a cellphone and allow the image to be exposed in some automode will get a lighter washed out look to the entire image causing the color of the soil to look light. Proper exposure of the SUBJECT and this isn't the case.