So fellow indoor plant intusiest. I decided to Revell against all your advice. I installed a T5HighOutput light. Only to show you guys to take risk, so here I go . I will post bi-weekly pics. Just to show all you negative folks, how well my plant is doing. ☺☺☺

Welcome Sebastiam and I wish you success with your plant. I am, however, confused about your reference to negativity...?? No one has yet posted anything, and typically ATP folks will be encouraging.

Yes, I thought Elaine's post was very informative. The thread "Dracaena marginata rainbow Help" in Ask a Question forum

I have my marginata in complete shade. But we get hot and humid out this way so maybe that is why it likes it? Most of the months outside it is up against an east wall getting no direct sun from the west as it is protected from trees. In the winter it comes into the house to the east (again) window) with minimal, if any, winter sunlight. It is thriving and flowering, too.
I wish you luck with growing your marginata and I hope your grow lights make your plant flourish.

The plant would like it more if you got the light much, much closer to the plant. And/or out the plant on some kind of stand so it is closer. Gene

Whenever increasing the light, doing it gradually can help avoid burning the leaves.

'Tricolor' is a cultivar name, and 'Rainbow' may be one I've not heard. It's not listed on this site, but that's not definitive:
http://www.triadplantco.com/li...

If yours was labeled with a cultivar name, it's full name is D. marginata 'Cultivar.' Can't see it closely enough in either discussion to know which it is. There's also 'Colorama' which is very similar.