Board Thread:Plants vs. Zombies Wiki Discussion/@comment-4009269-20140213201430/@comment-25363441-20140830185334

before the update every puzzle piece level (iceburg lettuce, twin sunflower, etc.) you can downgrade the zombies back to tier 1 if it's already tier 2 or 3. so you could win even if you use the crappy starter plants. because i have been playing this only for 33 days, this glitch helped me a lot in getting new plants quickly and quickly upgrading the available puzzle pieces plants. i called it downgrade glitch because i don't know what to call it because i just accidentally discovered it by myself. i don't know how everyone calls it because i haven't read it on this page i just assumed everyone knows it. with this glitch, on my 5th day of playing i quickly got the tile turnip which really help especially when partnered with the snap dragon. also helps because the card system was gone when i started playing.

when i got the winter melon i only use the glitch on magnifying grass lvl but now with the update the glitch is gone. :)