http://www.vrp.com/amino-acids/amino-acids/growth-hormone-amino-acids-as-gh-secretagogues-a-review-of-the-literature

According to this site, l-arginine and l-orthinine increase hgh significanty in a synergistic manner.

Also to note, apparently, l-arginine works better at night, not post-excersise.

http://breakingmuscle.com/health-medicine/what-women-need-to-know-about-growth-hormone-and-how-to-maximize-it

A bit more...

Arginine tastes awful, glutamine is tasteless, and glycine tastes like sugar. I don't know what ornithine tastes like since I think I've always mixed it with glycine. Glutamine converts to arginine so I don't bother with arginine.