Why 5 stars? because it's too easy, but takes too much time to understand how to complete the level.

Half a star because it actually works, and all levels are do-able, they just require some thought.
No more stars though because of many reasons.

1- I'll start with the BIG one- this is literally a rip off of PvZ. The playable characters are jpeg images of the plants and the NPCs are just poorly looped gifs of the zombies.
2- Sound effects are basic and get very annoying very quickly, not to mention the fact that the zombies don't have any.
3- There is no background music at all, this makes a bad game even worse because there is no atmosphere for the players.
4- The absolute worst thing one could possibly do (which you have) is to not even acknowledge anywhere that all assets are ripped straight from another game. (I know it's obvious but at least acknowledgement would be nice to see.)

perfect get a screenshot add some paint skills and there you go on the newgrounds hey admins at least you can act like you give a damn

cant even plant stuff what is dis???

Can't even pass the first level. Heck can't even kill the first zombie. Mabye it's just me? I don't know. 0/5.