There's a number of thing's it could be. Temperature fluctuation. The Make-up of the soil. Over Watering. General humidity and temperature. For starters your using peat moss which is acidic unless you add some kind of lime your soil will be very harsh. Have you tested your soil ph?


Another thing mentioned is the fan. Fans are vital to spaces with no ventilation but you only need very minor fan speed. If you have a dry room air conditioning will dry the fuck out of anything if left on. Try to increase the humidity and keep temperatures 75-80f day AND night, even low watt clfs can raise the temperatures into the 90's with no air holes.


Whatever space your using, leave it open to get fresh air. Turning your fan to the very minimum and generous watering will more than likely sort out your issue. Also if you can't consistently raise the humidity then keep in mind a fan will exasurbate that problem.