Here is the full list of all 9 Noxious Weeds Demo achievements.
Clear the Spring Scenario with Orchardist
Defeat the corn
Defeat 1000 Currants
Defeat 200 Owlnions
Harvest 30 Trees
Hold 600 water units at the end of a wave
Defeat a Pepper-Oni
Defeat 1000 Sprouts
Lose 5 times