Farming Seed/Crop yield rebalance

[Omega Haxors]

In the real world, the best time to harvest crops is before they've fully completed their life cycle so with that in mind I am proposing a huge balance change:
When you get to the endgame there's always a problem where your food yield is always way higher than you would realistically need, and that leads to high level players drowning in more crops and seeds than they could ever possibly need. There should be three stages to crops growth:

1) Young - This crop will drop nothing but one seed packet
2) Mature - This crop will drop the maximum amount of food (using current values)
3) Elder - This crop will drop the maximum amount of seeds (using current values)

The catch is that harvesting a mature crop will yield very little (10%) seeds while harvesting an elder crop will yield very little produce.
When you reach the end game you have to balance when to harvest your crops in order to ensure you don't end up with too much of one resource.

[Maelstrom]

That addresses end game issues but introduces difficulties to early game in choosing between harvesting for the now (food/produce) vs. harvesting for the future (seeds) makes early game dramatically more difficult.  It seems like your idea introduces problems while attempting to fix others.

[Thorfinn]

This is true for things like carrots, turnips and onions (though being biennials, seeds are year 2, which would really change early game), but not for grains, and especially not for the only one I really care all that much about, flax.

The end stage is easily dealt with. Just stop wasting time planting stuff. One greenhouse on medium fertility soil will produce enough that you have to throw away rot.