Add an option to seed bags to set two Q variables. Max and Min. Only seeds that match or are between those Min and Max values are allowed in that bag.
To easily identify which bags are which, you can change the colour of them too (or maybe you can choose from a variety of different colours when you craft them). Maybe you need Inkweed to dye the bag or special roots to get different colours.
So for example, you harvest a field. You only want 36 seeds higher than Q60. You right-click 4 of your seed bags and enter a number in there for Q Min of 60 and Q Max of 100. You colour code the bag to a nice reddish maroon colour. When you harvest, only seeds of Q60 or higher go into those bags.
But you want seeds for grass too, so some of the other bags in your INV you set a min value of 1 and a max of 59. You colour code the bag as the default brown. Seeds of Q59 or less then auto-go into that bag.
That way a farmer can harvest and end up with easily identifiable bags of High Q and Low Q. Any other seeds that don't fit within any Q limits go into INV as normal.