The tallest one is 92cm from the foot, that would be 3 feet and 0.22 inches according to Google
I read that they can get twice as big during the flowering stage, I really hope mine will not get that crazy because 1,80m (6 feet) flower is not what I planned.... but anyway I have a lot of vertical place so it will be possible, I'll just have to do more holes to hang my light
and welcome Freshsmoke,
just an small advice from my little experience, don't think that because you don't have super powerful lamp your plants will not grow like crazy.... 6 plants in 0.8m²=8.6 sq feet is a MAXIMUM (I actually planned 10 but got 1 hermi and 3 didn't germinate)