pretty sure when they say herb, that's their way of saying cannabis...
Also, we don't allow "what should I take" or even vaporize threads here in other drugs, so we can't suggest other options of what you should do to enjoy using your vaporizer, that's not what this forums about it's not a vaporizer enthusiast's lounge.
Why would it be unhealthy? I meant to imply that it is far LESS healthy than just consuming the tea as it was intended to be consumed, orally in tea form.. so that you get the most antioxidants out of it, which is what I wasn't sure you'd be getting if you put green tea in a vaporizer....
Also, wouldn't vaping tea ruin the taste of anything else you'd want to vaporize in there? I know that cannabis resin is easily cleaned with various solvents (I prefer to clean my glassware with a mix of anhydrous isopropyl alcohol, anhydrous acetone, naptha, rock salt and/or uncooked rice, and HOT water if necessary or if it's so dirty that the three incredibly powerful aforementioned solvents aren't enough to clean my piece, which has never been the case for me... Iso/Acetone/Naptha has never failed to clean even the dirtiest pieces in my experience)