leaves-plant location n.n.w. very,very dark. roots very ,very dark but lots of them coming.new leaf dark and darkening.direct sun light when no cloud up to max. 4hours.leaf has stopped growing at 75% of last one.leaf has purple tinge/strong on under side.new flower stem starting to come. using 7/2/2 fertilizer -cactus.
These links will refresh you on the care needed.