question about stem color

[browntown420]

one of my plants started displaying a dark purple color near the top of the stem , and some leaves which had just sprouted were turning purple as well. is this a sign of a chemical deficincy or somethin?

[bonbon]

http://www.cannabase.com/cl/bcga/bcga/nutrients.htm

[bonbon]

Cold grow room temps can cause that also....bonbon