Due to the way croptopia handles harvesting you always end up with +1 seed from your crops. Meaning if you start with 1 iron seed in less than 20 min you can have 64+ iron seeds , which kinda breaks the balance of the mod.

they can also be planted on any farmland ... if i understand correctly, the intent was they should only plant on "essence" farmland or such? there is a customization to edit the percentage of the "secondary seed" : https://blakesmods.com/docs/mysticalcustomization/editing-crops which in effect is now 1.0 (100%) as played right now.

or such? there is a customization to edit the percentage of the "secondary seed" :

Its not the Secondary seed chance that's the problem it's how croptopia handles the harvesting mechanic. Always gives 1 seed back after harvest.

Edit: The second seed chance only counts when "normal" harvesting (Breaking) , not with croptopia harvesting (right clicking).

Dang thanks. next update we will have to disable Croptopia right click to harvest.