First time grower: Strange Coloring

[Psykoface]

Hello!
This is my first time growing outdoor marijuana and I have noticed a change in color of my plant. The stems have started turning purple. Also on the top of the plant the stems seem to be white. I have not used any nutrients, as the soil I used is supposed to have them already. I've been watering the plant once every 3 days with approx. 1-2 liters of rainwater.

 

[Conradino23]

Nice sativa, man. Seems ok to me

 

[CO Finest]

Two things on my plants cause that turning purple stems.
Temps getting low (bellow 70)
magnesium deficiency

 

[Antics]

Welcome to

This will help in adding photos: Clicky!

420 Magazine likes to have all photos uploaded here, that way they're always available in the future.

As for your question, I believe the fan leaf stem turning purple is normal. I've grown a few strains, and all my fan leaf stems have gone red/purple in fairly ideal temperatures 68-82 F, 20-27.7 C.

The white color looks normal, considering it's newer growth.

Leaves themselves will turn purple on some strains when night time temperatures get a lot colder, somewhere around 55 F, 12.7 C

But your plant doesn't look bad at all, I don't see any serious issues. Keep up the good work!