So I saw this in a Twitch streamer's video, and having considered making a weed based game myself, I was wondering how this would be designed. I must say that it actually played better than I thought it would. The neatest design decision was to make the fertilizer come from the weeds -- it makes them a hazard that you can't just ignore, but need to keep in balance.
My first playthrough I was just trying to learn the controls, during which the weeds got everywhere fast. There was no recovering from that, so I reset.
My second playthrough I got to 13 carrots before being overtaken by weeds. It took me a bit to learn the mechanics, and the controls were somewhat confusing (I'm very glad those were on the screen the whole time, though I think there might have been a way to simplify them so you don't use three action buttons). I also noticed here that the music speed increased with the more weeds on screen, which was very effective at inducing anxiety.
But finally my third playthrough I was ready. I was doing remarkably well on these weeds, to the point where I really didn't have enough fertilizer to do anything. And then like usual, the weeds go outside the bounds of the farm, which is the point of no return and when chaos really begins. But I managed pretty well, and got all 25 carrots. It might have been nice to not have a message pop up over the screen obscuring my view while I tried to see how many carrots I could get (though it didn't really matter anyway, since 2 more carrots picked later, the weeds were everywhere and the game was lagging intensely).
Anyway, cool game, it was more fun than I expected.