Plant movement is fine, just initial placement is abit goofy. I am on desktop.
Also a big plus would be a boost in contrast in colors, the plants looks the same color as their environment. If instead they were more, or grew more saturated as the game progresses to emphasize the cleansing and growth of the environment, as well as mixed with a post processing that starts off less, and grows more contrasted or saturated (whichever looks better) to really sell the growth, that would add additional cherry on top.
Also the UI seems abit small in comparison to the actual game, if this is because it does not scale with resolution (as I am on 1440) you should consider making your UI scale with screen size. If it does scale with screen size, perhaps consider making it larger, because it is puny for me.
Additionally, it would be cool to see the plants not position themselves on top of each other by default, because once it gets to cookie clicker mode you just get a few hundred plants stacked on top of each other. It would require some coding but I know it is doable to perform checks and recursively move the placed plant outside of boundaries until the distance check on it is happy.