It has nothing to do with the way it's grown, sometimes it's just genetics. I've had seeds straight from Amsterdam like purple nurple for example or blue cheese straight from Big Bhudda himself, and when I grew it out it was just some super funky beautiful green nuggets. That doesn't mean that it's any less potent, and it's still the exact same bud, it just wasn't in their genes to turn colors on ya. An example of it being a product of how it is grown, would be a strain called The Black, from Paradise Seed Co.. It will turn a hazy dark purple, almost black color In the last 2 weeks of flowering. But if you like that more psychedelic, heady high rather than couch lock zombie style, you have to harvest before those last two weeks, before the trichomes go completely Amber. So you won't get black buds. But again, if you let it grow out for those last two weeks you will have some stunningly dark, beautiful bud. But even in THAT case, there are some seeds that won't turn color for
You in flowering. That's just the way nature is. Hope that helped a little bit
**EDIT**
After reading the whole thread, and seeing a lot of interesting opinions, I also saw that the question was answered more or less in the same manner as my answer, so apologies for the repeat. But yeah, if someone grows a purp strain and it turns purple, and decides to turn it into a mother plant rather than flower it out, or even just take cuttings, those cuts or
Clones will ALL turn purple. Because it is predetermined in the mothers genetics. This is what most perpetual growers do, they will buy a pack of seeds, grow them out an find the absolute best plants of the bunch, and keep them by cloning. I was a longtime member of RollitUp.org, and was a perpetual grower myself. I grew mainly OG Kush, Chemdawg, and Sour Diesel, but I also went through a huge variety of strains before deciding on what I would grow for
The long term. I would love to discuss perpetual growing with anybody who is knowledgeable on the subject and compare notes.. I was a Stinkbud method grower, and before that used the SOG method which is inefficient if ur limited on space...