[David]

My experience with sp. viking also tells me so... that the picthers needs to be hidden in the dark for it to produce the vibrant dark red colours. However, the leaves should be exposed to sunlight.

They remind me of N. ampularia in the wild where the basel pitchers are totally cover by detritus and other plants but the growing stem is exposed to direct sunlight. In these conditions they pitcher well and the pitchers also has the most colours.