Light – Even though light is necessary for the growth and assembly of fibers and in order to produce
mushroom caps, it is not essential for the mushrooms’ growth. On the contrary, light darkens the
mushrooms’ color, unlike growing them in the dark (which whitens them). Although just an aesthetic
difference, color considerations can be important for the marketability of produce, for example, white
straw mushrooms are much more popular among consumers than darker gray crops.