I start mine outdoor from seed with no problems. You started yours indoors so it's best to do a transition to the outdoors. For a 2-3 week seedling it wont take long to harden off. This can be done in 3 days. First day move it outdoors in a protected shaded area. Second day you can move it to some early morning full sun for2-3 hrs. Then move it back to the protected shaded area. Then in the evening you can move it back out to the sun for the last 2 hrs. Third day give the plant full sun for 6 hrs from early morning. Then move it back to a shaded area. That will make it safe for full time sun from then on. IF the days are all cloudy being outdoors for 3 days on cloudy days you can still give the plant full sun on day 4.
The purple on the leaves is from the genetics not a deficiency. It's a specific genetic predispositions within the species. The banana mash auto the purple hues are a recognized aesthetic feature that emerges in many specimens.😍