Frank Mamone wrote:

What is the proper procedure for pruning stem plants?

Do you trim the tops, re-plant the trimmings, and remove the remaining
bottom?

In general, yes. Each plant is different, but lots of them put out roots
at nodesm and rooted clippings are a tad easier to deal with. Other plants
start to branch out when they hit the surface. For most of my plants, the
bottoms aren't worth keeping. Watch your plants and you'll figure it out.

Her are two Karen Randal articles that will help:
http://www.animalnetwork.com/fish2/a...ic/default.asp
http://www.animalnetwork.com/fish2/a...ic/default.asp