The greenhouse is a building in Plants vs. Zombies Online. It is used to upgrade plants, similarly to the upgrade system in the Chinese version of Plants vs. Zombies 2 . To upgrade plants, the player has to complete certain objectives within the game, have a certain battle score which depends on what plant is being upgraded. It is unlocked when the player reaches level 5.
- In older versions, only tutorial plants and Ancient Egypt plants could be upgraded.
- In addition, the player had to use Upgrade sun, a special currency obtained through completing levels or daily rewards, to get upgrades.
- Plants obtained in East Sea Dragon Palace cannot be upgraded via the Greenhouse.