Well, feeding manyus to lvl 30+girls starts being too expensive if you uselvl 5 manyus. If what you want to upgrade is beyond that level, you should try to farm the advanced garden if possible. Depends on if you are able to clear 10-5 and 11-5 (don't try to 3* them yet).

And yup, evolving what has hit max level is a good idea. I think those teas shuld suffice to farm advanced dragon stages, maybe with a good helper, at least all but the magic one, since the boss changes depending on the element of dragons you are farming, and magic bss is a tad stronger than the other 3