It doesn't matter the specifics of the number. Just start counting the sets when you feel it's heavy enough or is close enough to your goal weight. You can do several warm up sets with 60, 90, etc...whatever you want. But once you get to say 150 start counting the sets, jump by 10 lbs each or whatever.
You also need to be doing to assistance work, like cable pull throughs, good mornings, GHR's, Reverse hypers, ab work, etc. And that's just assistance/work for deads. If you also want the row to be a lift you want to bring up, you're going to have to do a lot more assistance, like curls, cable rows, db rows, etc. If you want to get better at rowing, you're probably going to have to row two or three times (for a big compound lift) in a training session.