I got stuck on the area right after being able to create plants and wasn't able to get any further but the sound design and art in this game are so likeable, was really fun to play and I'll probably come back later.
SPOILER:
It's really hard, but you just have to make grass to the next platform (don't go on the grass yet.) Afterwards make a rock and push it on the grass to the next plat. Put the rock on the button and begin moving to the second rock. You must make a diagonal jump to get behind that rock. Push the rock into the button and you finish the part.