It won't regrow leaves on the stem below the living leafs. If you want a fuller plant or don't like the bare trunks, I recommend propagating the whole thing and starting fresh! As is, it looks like something you'd find in Whoville! Kinda funky and cool looking. Let the soil dry pretty significantly before watering again and avoid direct sun. Good luck!

Looks like this is planted directly in that ceramic (?) pot which I suspect doesn't have drainage holes. I would gently remove it and repot into a container with drainage; you could choose something that will fit into the ceramic pot or something a bit bigger - but it must have drainage. There are three stems, and while none will grow leaves on the bare lower stem, two are shorter and their leaves should fill in quite nicely, leaving only the bottom 18" or so with leafless stems. The plant will tend to do that anyway; drop lower leaves as it grows more at the top. If you want something more leafy at the bottom, you could just cut all the stems off about 10" or so from the soil, just above one of those white lines across the stems. This might even result in a couple more shoots coming from the bottom, for added leafiness. And when watering, always let the soil surface dry out, to about the depth of your first knuckle if you push your finger into it, before watering again. It actually doesn't look too bad and will probably recover completely; good luck!

Hi Conny! Thanks for your suggestions. The pot does have drainage holes, thankfully! Do these like to be root bound (meaning, I should report) or can I just cut down the large one to the same lengths as the other and put the cut top in with the others in the existing pot?

I think I agree with Matt that four or five stems in this pot is enough. If you decide to cut the long stem down, you can always cut the piece you remove into sections to start new plants, in a different pot, if you like.

@Matt: Yes, the plant had been hidden behind a curtain to keep their young kids away from it (for about 2-3 years). I was nervous about shocking it so I've been keeping in a very indirect south exposure. I suppose since there's hardly any leaves on there, I could quickly move it to more exposure! The existing leaves are now slowly yellowing and the curled ones aren't unraveling. I will probably cut all the stems back and start from scratch :(

@Conny: As you & Matt have suggested, I will put the new section into a different pot. I would LOVE to have a couple pots of Diefs!

Let it also dry in between waterings. Watering every 1.5-2 weeks. When you propagate the stems. Kepp the soil most but not wet /soggy. Good luck with them.

Thanks Matt.

A couple more questions: I've never cut anything this thick before. What kind of shears or knife should I use to cut it? Or does it matter--as long as it's been sterilized? And would you cover the open wound with anything?

You might want to use rooting hormone. Maybe someone else can chime in on that I don't use it but know it works. It's best to use a scissors or the hand gardening pruners something that is sharp and cuts with one wipe. You shouldnt' cover the wound.