I brought the LIVE TROPICAL MOSS from Black Jungle in aug, and that stuff is doing great. I thought it was going to die. It is a lush green. It comes in a thin sheet and cost me $26. They said it grows but I havent seen any growth as of yet. However its only been a month. Maybe you should try some Java or Ricca.
Best ground cover for your frogs(and in most cases for you too) is leaf litter. Your azureus will trample most any kind of vascular plant ground cover. That being said, if you have your heart set on a green carpet, the best thing that I have used is the moss that I find growing in orchid pots. I'm not talking about decorative moss. I'm talking about the stuff that volunteers in mature orchid pots or on the soil of other greenhouse plants. For me it is very hardy and spreads quickly once it gets established. It is also free with the purchase of the right orchid.