For me, I think the issue is more horizontal than vertical space. I agree about N. jacquelineae and N. hamiguitanensis being sort of sad if you don't have space for uppers. The reason I say I have space for, say, N. dubia is because I already have a fairly tall terrarium (18"), so I can give it some vertical growing space. However, these plants usually take up a significant amount of horizontal room before growing vertically, and ones with larger pitchers take up more horizontal space. Based on the pictures I've seen of N. Dubia, inermis, tenuis, etc. they could grow vertically for a while in a tall terrarium, especially if trained to grow a little bit circuitously, like they do in the wild, rather than straight up. For example: 10cm=4". Suppose the pot is 4" tall. I can get three internodes' worth of growth just growing vertically. If the climbing happens along a non-vertical structure, I should be able to get at least four or five before having a problem. That gets tricky with other neps in the terrarium, but I think I could get it to work. However, N. jacquelineae, before beginning to vine, has something like a 2' spread (right? I might be misremembering), and many other plants are similar. So for those, I don't really have the room at the moment, and would only have the room, in the foreseeable future, as a windowsill or outdoor plant (during the summer). I've read that with certain specific care changes, they can do well under these conditions as long as the base humidity is not too low, but I also won't necessarily have even enough room for that within two years. All of which is to say this is very helpful into
I will have to stick with species that have a small adult horizontal spread for now. I know that for a tall terrarium I will need to put the plants closer to the light until they get taller. Is there any part of my logic that's wrong? Also, internode length seems like it should be related to growth speed--is that true?