all strains are different. do you have any light leaks? that would slow flowering. a month with no buds is rather unusual, unless it's a really long flowering sativa. this is my gypsy's kiss at day 28 of 12/12. it should finish in 65 days or so. also at 1 month the leaves should not be yellowing yet, especially if it is a sativa that takes a long time to finish. but you did say you had never fed it right? i'm suprised it looks as good as it does if that's the case. mj is like us, it needs food to survive and flourish. just start slow and work your way up. with no ferts the flowering would be extemely delayed as the plants have no nutrients to produce buds. my seed plants usually start to show defficiencies(spelling) at the 3rd week of vegg if i don't give anything but r/o water until that point. that is why it suprised me to hear a plant of that size had never been fed.

some sativas can take as much as 120days to finish!!!!!