How long do you leave a teabag in water?!
I have three boxes of various green teas.
One box says 1 to 1.5 minutes. Another says 3-5 minutes. I would go with at least 1.5 -2 minutes.
first of all, make sure the water is not boiling hot. green tea needs a bit cooler water. probably around 180-190 F. i'd steep green tea for 2 or 3 minutes. Then adjust accordingly.
For about hour or less it is best beyoond it changes the taste