I think that if players go through the hoops to grows seeds (and it isn’t nothing), then they should get some seeds in return. after all, its how actual plants work so it would sit well in player’s heads. I understand that it would diminish the need to explore, but that’s the point of farming. surviving in any harsh land means moving from gathering to cultivating. As for gameplay, it could be the reward you get for a well fortified and stable base and if your destroyed, then you have to restock your cabinets with plants.
ways to prevent an endless loop of regenerating plants would be to have only one plant and seed be produced per seed so that players will have to still search for more seeds to put into rotation if they want to produce many potions and such. if seeds, were then, a bit rarer, then there’ed still be scarcity, but a way to farm and achieve a detachment from the greater, but more difficult (and perhaps tedious) tasks of venturing out each time one needs ingredients.