I believe they grow from the crown not from stem segments. They get fuller from the base up.

Penny

Thanks. I'll leave it alone.

Sharon, I believe what Penny is saying is that if you want it to get fuller, remove the stems down to the crown. You should be fine to prune to the crown and then you can root the trimmings!

This is my first year gardening. I have two Lobelia Cardinalis plants. Is there something I should do to winterize. Should I cut them down to 6 inches or so? or just let them be. Thanks!

I don't cut any of my perennials back up here in my cold zone. I let them die off naturally and leave them as is until spring at which time I remove all dead or damaged stems, etc. This provides more protection to the roots of the plants as freezing snow or rain can't get down to the roots and cause the roots to freeze.

Penny