- For the international version of the level, see Lost City - Day 21.
- For the level after the v1.8 update, see Lost City - Day 21 (Chinese version).
Lost City - Day 21 was the 21st level of Lost City in the Chinese version of Plants vs. Zombies 2. It was a Unsodded level. There were lots of Gold Tiles in this level that the player could use to obtain more sun. When this level was finished for the first time, the player got a star.
The player will be forced to use multi-directional plants, like Threepeater; plants that deal splash damage, like Melon-pult, or plants that can attack anywhere, like Banana Launcher. This can be difficult to adapt to, especially with the Level 4 zombies, the zombies present, and the amount of them that spawn on the top or bottom row. Snapdragons will greatly work in this level, as it will provide cheap damage early in the level. The tremendous amount of Gold Tiles will easily let the player get powerful plants out earlier.
- This level contains the most Gold Tiles in any Lost City level.
- The concept of this level is based on Unsodded, a scrapped mini-game in Plants vs. Zombies.
- This level and Player's House - Day 2 are the only levels with 3 lanes.
- * A gate can be unlocked with a key after completing this level
^ Conjectural name