[TNhobbyfarmer]

Even if you mow the tall grass first, you are probably going to have one heck of a time with the plow clogging up. My thought would be to cut it first, spray with roundup, wait a few weeks, disk it a time or two and then plow. I know that sounds like a lot of time and effort, but there's a chance you will be very unhappy with the project during the work and the finished product once everything is done. This may be something you want to work on this year with an eye toward next spring as a time when all the work and preparation comes to fruition. Good luck. As has been mentioned in previous posts, plowing can be lots of fun. But beware, it can be frustrating as well. Don't ask me how I know that.