Stalk and stem turning red

[Iron_lung]

I have an unknown sativa that is outdoor in soil just showing signs of flowering 3weeks in and the stalk and stems are turning red , vegetation looks good? Should this be a concern or is the plant lacking something. Help

 

[Iron_lung]

?

 

[Medical4Ever]

some sativa strain display a uninqe color but if your vegation is good and the growing process has not stoped it could be portraying a natural color change do to the season

 

[Hightide805]

are your leaves turning yellow also? you might have a nitrogen/sulfur deficiency