What you should do is find a spot outdoors at least for the growing season. It is challenging to reproduce adequate light artificially for one plant. What species of Agave is it?

Closest guess so far is Furcraea selloa marginata, however I got it as a seedling from a friend who also doesn't know. I have a small "balcony" outside my window on which to put plants, but no garden or anything nice like that. My only worry is that it can be fairly cold (between 8 and 20°C) and very rainy during spring, summer, and fall with about 3 weeks of sun in between. Would such a climate still be okay for it?

This Genus grow in our South Western States and down into Mexico, the grow in deserts, on hills, sides of mountains, high and low elevations. I understand they also grow cultavated in other States and well, If you are sure of the name I can look it up for you. I don't think farcraea are of the same genus, though they are related to Agave. Norma