Fun game and a nice take on the theme! It was pretty challenging, but I managed to power up the sunflower eventually. It really wasn't intuitive to me what the plants did, even by the end. One slowed the enemies down, it seemed, and the other (the blue one) I never figured out. I kind of just dropped plants around randomly.
I tried to survive the sequence after the sunflower part, but health started decaying too quickly. Is that meant to be survivable?