When do plants physically grow, is it during the daylight or night cycle? Casual obsrervation of stem plants in my tanks seem to indicate that they are taller in the morning than they were the previous evening. Is this correct ?

I definitely see growth overnight, especially in anubias. But, I also see growth during the daytime. My guess is that plants grow 24/7.

Elongation and growth are different terms.
Growth = more mass, so more dry weight.

Plants grow all the time and do different things relating to growth at different times.
But it's all part of the overall process.


Regards,
Tom Barr