I have had my tank set up for over a year now, and though I have had stems "grow" ok in my tank, I have struggled with them not looking like total crap. I have cabomba, wisteria, bacopa (moneywort), and have had some other miscellaneous ones. My cabomba, wisteria and bacopa grow just fine in terms of length and reaching the surface, but they look like total crap. They never grow uniformly, usually just one or two stems stick out like a sore thumb, and when I trim them they never grow "bushy" like people say they should. My wisteria gets holes in the leaves as well.
I have a 24w t5HO with a hardcore reflector about 6" above a 29g tank with no lid. I change the water every week and have experimented with using Rootmedic Liquid ferts regularly. I also use root tabs. Nothing works, and I actually hate the stem plants in my tank because they look so bad.