Please use this thread going forward: [GTW] Scientist: Plants at science lab don't produce harvestables | EA Forums - 5038711
Unfortunately the bug has been present for years and will likely never be fixed.
You can use cheat commands to get around some of the tasks. Turn on debug cheats, shift-click and select things like growth stage or moisture. Set moisture to dry and you'll then be able to assign someone to garden it. Problem is, cheat commands will not cause fruit to grow, so NONE of the plants on the science lab lot will EVER grow fruit. But I get around that by growing the plants on my home lot and just carry them to work if I need them for a potion. At least the plants can still have samples taken.
Screwed up thing is, even though plants won't grow, they still die. So, eventually, if you are at the lab long enough, you will have no more plants and be unable to grow more.
There aren't any mods to fix it either. So, I think we're all screwed.
