Citric acid---would not have thought of that......would think that you could also use GSE or food-grade hydrogen peroxide mixed with water to spray on to keep mold down.
I'd bet everything on the temps. I've had two identical trays growing in diff't areas and the warm ones grow quicker. Also, in the winter, within one tray, the grass closest to the cold window, take longer, so if I forget to rotate, I really notice a diff.
I've heard of those warm trays, and kind of feel they're like electric blankets. Not good for humans, so I was thinking prob not good for plants either. I do bet the warmth from them helps though.
Visit me on Facebook at Mary Kay Simoni
highest weight ever 147 lbs.
Mar 2010 - 140 lbs.
Sep 2011 - 128 lbs
Goal - 115