Plants grow during the day AND night. During the day, they use sunlight and CO2 to make sugars, which the plants store and use for growth. During the night, plants use the stored sugars made during the day and combine them with O2 (Oxygen). Most of the cell growth is done at night, and plants tend to stretch or grow more during the dark phase. This is why growing under 24/0 produces very compact plants, while shorter photoperiods, 18/6, cause them to grow taller. This is an oversimplification of what goes on, but it is essentially correct. Plants will also lean towards the light, which is a slightly different process that relies on intensity of sunlight to regulate growth. More growth on the shaded side results in the shaded side pushing the exposed side, which happens to point the growing top of the plant towards the sun. It could almost be said that the sun/light can act as a growth retarder, instead of the dark being a growth accelerator. 6 of 1, a half dozen of another. If any contrary information is available, please feel free to post it.
