How much tulsi tea (indian basil) should I drink per day to help with depression and anxiety feelings?

See the long answer. I am not aware of the constituents of tulsi tea, but the question which needs to be asked 1st is: what is the severity of the depressive episode? Some studies have indicated that certain herbal remedies - ex. St. John's wort - may be helpful ways to treat a mild depression, but antidepressant meds are more appropriate in the treatment of more severe episodes.