Deficiency or just a mind error?

Most likely cold.i have personally never seen a Amnesia getting purple like that.i know that some growers at last flowering process use ice to make plant stressed with cold to get more red and purple buds and leaves.but only with purple and fruity types of plants.like banana blaze.. blueberry. I guess it's not something with feeding or water then u new what it was.not you're first grow😉😉

Apparently no one say that you said purple flowers as well. It’s likely purple punch or the lsd.. but I did have a amnesia turn purple late flower.

There are SO many things that can result in purple stems - certainly genetics is one of them... but there's also stress, nutrient deficiencies, temperature fluctuations, fungi, ph imbalance... in short, there's no way to tell if this is Purple Punch or you have some issues! I see you actually have 4 different strains going on this diary - in the future, it's best if you put a label on each different strain if you're growning several together - that way, you'll always know what strain you're dealing with! Good luck, mate... I've got a similar problem... ordered 5 seeds of a particular strain from a seedbank and 1 of them is absolutely positively NOT the same strain (she's indica and the other 4 are sativa)... but there's no way anyone can tell me what that strain is... the best I can do is to give some nugs to a friend who is an absolute connoisseur of weed and he MAY be able to at least get me in the ballpark of identifying it!

I believe the purple stem is genetic. Nothing to worry.

Purple stems indicate primarily 2 things as far as I know. One is genetic, the other is temperature fluctuations. If the temp at ''night'' is too low you'll end up with purple stems. Or maybe you mistake them, who knows? Ahah