What really causes Purple in plants

[Mazzariman]

Howdy folks. I grow outdoors, and I have been selectively "breeding" my plants over many years, to produce the traits I desire. Mainly I'm going for purple with indica dominant traits/qualities, while trying to minimize (breed out) the sativa influence. Often I hear on the site, that nutrient deficiencies, stress or what not, create the purple. If my plants are getting the exact same soil, nutrients and conditions, are the purple characteristics that are showing in some, indicative that I'm on the right track to achieving something like purple indica? I am consistently producing seeds that give rise to plants that show purple from the early stages on through flowering. to note, all my seeds originally came from my pals from when I lived up in Humboldt from 1980 - 1996, and were from the popular named strains (GSC, Trainwreck, Headband, Ooey Gooey, etc., along with some original Afghani, Mazar-i-Sharif and stuff from the early 80's pre clinic if you know what I mean). Of course I've always taken my best male each year and used his pollen to fertilize, so I have absolutely no idea what my plants really are named. I create my own names for each female and save her seeds (i.e. Frosty Girl, Early Girl, Nasty Girl, Purple Girl etc.) Each year I start with ripe seeds from my collection and see what turns out. I regularly end up with a somewhat diverse batch of gals and dudes (no hermies allowed!). Here is my current group. They aren't huge, but they're doing pretty nice for this time of year. I topped these instead of training the main stalks like I usually do. No Christmas trees this time.

Would these be showing purple due to any deficiencies or through my breeding? Dang,the smell of em is awesome.

[kingfish]

I found that when my temp drops to 55-60 degrees late in flowering it turns the leaves purple. I grow mainly Hybrids so I don't know if it is Sativa or Indica dominate.

[SoOrbudgal]

My glues do, GSC do an some of my kushies

[Floopydoop]

Don't know what makes it other than genetics, but purples generally aren't a favorite of mine to consume. Effects are really light on me for the ones I've tried. Probably just got bunk from the dispo, but not a fan overall. They do look really pretty though

[DeadlyFruit]

I’ve always been under the impression that it is one part genetics and one part temperature shifts to colder nights. Clearly if the genetics are stronger it can go purple earlier but generally speaking it happens during flowering when the nights are cool. I have no scientific evidence to back this up, it is just what I read and then observed. All the really purple plants that I’ve had followed this logic and were grown outdoors so arguably it could be something else in the outdoor environment but I am still leaning towards cooler nights during flowering for plants with purple leaning genetics. If you discover anything that says different I would be very happy to learn. Great looking plants by the way!

[gbauto]

I think that genetics can play a major role in expressing 'purps'.
I have a pheno of Primal Punch that throws purple veins on the stems, even in veg.
None of the other pheno's exhibit that trait.

[grouchyoldman]

Yep, I've seen side-by-side grow logs that produced intensely purple colors when plants were exposed to lowered temps during flowering. I just tried this on a White Widow plant grown indoors and the results were impressive: witness "The Purple Widow!"

[panalilies]

I was reading about temps on a post and came across this-

https://www.growweedeasy.com/temperature#seedling-and-vegetative-stage

[SoOrbudgal]

Yes indeed it happens and is a lovely effect.

[Puglover1]

If Mag Landrace seeds ever become available you should try it. It's a purple indica.

[Mazzariman]

Thanks everybody. Since I started these outdoors in a makeshift light enclosure in early winter (see pics), I was thinking the cold weather could've helped them to show purple. Why some plants growing in the exact same conditions didn't show purple, has me leaning towards genetics as confirmation of my breeding for this trait. Since the Hindu Kush mountain range has hot days and very cold nights, I would think that my indica dominant plants would respond to these similar conditions where I live. We can have super hot days and huge temp drops at night. I have some new starts that are behaving the same way. Some are showing purple and some aren't. All are healthy and growing well. I'll get pics of them soon enough. I appreciate everyone's input. Thanks again!