leaves of my plants are loosing color slowley, turn yellow, sometimes develop brown stains and eventually fall off. It started in middle of the plant on lower leavs and then spread.
It is common and normal for older leaves at the bottom of the plant, shaded from light to yellow & brown. It can take some experience to learn how much is normal and how much is a sign of a nutrient deficiency. It also makes a difference how old the plant is. A few yellow bottom leaves on a plant half way through flower is different than yellowing leaves on a 3 week old plant in veg.