I have been trying to get plantsims since I started playing with Sims 2 in spring 2020. Two of my Sims 2 characters, in separate households, spent their entire lives from teen through elder keeping large gardens and spraying for bugs at every opportunity. No plantsims. In Sims 4, the founder of my longest legacy so far spent her whole life AND her ghost life over the course of the whole legacy searching Patchy's pockets every day and ordering lots of rare plant seed packets. She had I think 3 magic beans by the time I wrapped up that save after 5 generations. So, the new scenario makes plantsims available to me for the first time <3
A good gameplay way to do it is to put the stump on a community lot somewhere (I like to place it in the Sylvan Glade, but you could place it anywhere more hidden away). Sims from around your rotation or successive generations can add the beans as they find them. Once the beans are found and the tree is grown you can have the sim(s) who added them turn into PlantSims and maybe have a gameplay rule for who gets to turn in the future.
I do something similar with the wishing well. It doesn't fit many places, but it does fit at the Ruins in Windenburg. I like to place it there and my sims only get a wish if they are invited there and attend.
If you are willing to use mods, you could also use TwistedMexi's TOOL mod to move it somewhere even more remote. I originally did what @Emmavane said with the stump but moved the tree to a more remote place with TOOL recently. If you haven't used TOOL, or haven't used it in quite a while, it's super simple now to move things with it compared to how it originally worked.
The other advantage of doing it that way is it makes it not tied to a specific lot being loaded. I have it in Glimmerbrook in my game, but have considered moving it to the Magic Realm. It would so work being next to that abandoned greenhouse.
I finally got my game working @Stormkeep. I used the nuclear option on all of my mods except MCCC. I'll just re-download all the stuff I want and need. So, I created a new plantsim, meet Blossom Bledsoe....
@SimCrazy Delia's tattoos are great! and the toddler plantsim is adorable. How did you create her? In CAS? @DaniRose2143 Good luck this time! Nice branch shadows in those photos. Good background for a plantsim.
(I wonder if more people out there have male plantsims? My poor Travis is feeling outnumbered XD)