I started mine off on 24/0 for the first 3 wks and then switched to 18/6 for the last 2 wks...i had 27 female and 25 male...when i was growing outdoors i had 75% female...so i would say 18/6 is probably better...but then again i'm growin bagseed now and when i was outdoors i ordered the seeds so that may be the reason.