The yield will be subject to seed,growing medium,and growing conditions.After 3 months of tracking and expieramenting with differant soil augments and amounts.I found what worked for the growing conditions in my area.If you are harvesting 6ozs. a flat of 21/11inch. your doing fine.But as with all things in life there is room for improvement.You didnt mention how much seed per flat,size of flat,growing medium or how much medium?Growing inside with growlights,or outside,to many variables to comment on why your yield is only6ozs.However that being said better seed + better soil along with some other mods to your growing tech. will improve your yield!I am aveaging 10-12ozs. per flat of wheat and barley.Feel free to shoot me an email for a more detailed breakdown of my growing tech.Happy growing and good health!