Flower not developing on marijuana plant

A question from a fellow grower:

I changed the cycle to 12/12 45 day ago but the flowering has been not developing….the leaves are very beautiful, the soil ph is around 6,5thses thing sound good, but I don´t know why the flowers is not developed.

Are you absolutely sure the plant is getting at least 12 hours of solid uninterrupted total darkness per 24 hour day? The schedule needs to be reliable and consistent as well as the dark period not being interrupted at all.

Also the picture is a little small, I can’t really see the health of the plant very well but there does seem to be some red in the leaves’ stems, this might be nothing depending on the strain but it could be a sign of a nutrient deficiency, these types of things can delay flowering.

I hope these thoughts might help.