I don't know if I'm doing something wrong or something else is wrong but I have to press the number keys several times for the tool to actually switch. It would be nice to be able to switch using the scroll wheel.
It's also kinda hard to know if I'm clicking the right place for the tool to be effective. I believe some feedback regarding that would be nice (maybe area of effect or plant being highlighted?)
The art is very cute. I missed some sfx.
I agree with Ethan Samuels' suggestions too.
Keep up the good work!