Here are some challenges.
Tell me through comments if you completed one of the challenges.I want proof if you completed one.Make sure you understand what the challenge is if you completed one.I will put your username next to the challenge with the word "winner" if I know you completed that challenge.
Fill up the entire screen with plants that cost 100+ sun.
Defeat the Zombie Yeti.Winner, Zombie8888
Get all the Zen Garden items.