Judith,

The best time to do pruning is when they are actively growing. If you see that they are under your light set-up, then it would be fine.

When you prune, it can help w the caudex getting larger. This may happen. Sometimes when we cut a taller plant the caudex only gets fatter, because we have arrested the top growth until it begins to grow again. Where to prune is a personal choice on you part. If you prune lower down, you can get multiple branches giving a shrub type look. Higher up would not be as appealing.

If you find that there are longer spaces between the internodes (leaves), this can a light, fertilizer or just genetics. Short spaces between internodes is what is really good to have.

The caudex will get bigger as it ages either way. If any of your plants are destined to have really stout fat caudex's, it will happen through the genetic make up if the individual plant. Such as the one in photo (front, black square pot).

I have pruned many just to experiment and some of the really tall ones, just produced more lower branches, but the caudex did not necessarily get large.

Rick

rcharles_gw, I must take issue with your statement that "Higher up would not be as appealing.. This Pinterest photo of a tree-like plant, laden with a huge bouquet of flowers, and of the twisted trunk plants might change your mind.

Paradise what rick is saying is his personal choice is to cut back the long straggling branches to make the plant form secondary branching or back buding most DR growers grow the plant for the caurtex, by cutting the long branches back makes the plant look more stocky and causes vigorous regrowth. The two plants that u have put up are just different techniques in which to grow a DR which look nice but you can notice the caurtex is not swollen i would be surprised if rick has not grown both types :×)