- For the version in Plants vs. Zombies 2 (Chinese version), see Plant upgrade system (Chinese version).
The plant upgrade system is a feature in Plants vs. Zombies 2, introduced in the 5.7.1 update. This system allows you to level up your plants, which increase their capabilities. Plants can be leveled up by collecting seed packets, which are obtained via Piñatas. Piñatas can be obtained either by completing quests in the Travel Log, or via purchases from the store.
Although leveling up plants usually increases the plant's capabilities, or statistics, not all plants' statistics are increased per level. The player has to spend a lot of coins to upgrade each plant, with the cost of each upgrade increasing with each level of the plant's upgrade progress. The maximum level to which each plant could be upgraded was 3, 4 or 5 for the 5.7.1 and 5.8.1 updates, raising to 6, 9, and 12 for the 5.9.1 upgrade. As of 6.6.1, all plants will be able to achieve level 10, 15, or 20, depending on the characteristics of the plant.
Some benefits of leveling up your plants include a greater toughness (damage sustained), higher damage output, faster recharge times, decreased sun costs, or a greater amount of sun produced. Many plants also have their own unique benefits from being upgraded.
Do not upgrade plants which you will not choose to use, as it only wastes coins. Upgrading instant-use plants is useful, because instant-use plants usually take a long time to reload. Upgrading them will allow you to deal more damage, and also to plant them more frequently.
Suggested plants to upgrade would be expensive plants like Winter Melon; area-of-effect plants, such as Snapdragon or Fume-shroom; sun-producing plants, such as Primal Sunflower and the aforementioned instant-kill plants, such as Cherry Bomb. It would also be wise to "level-up" specific plants that can be used to assist with levels that are particularly tricky, such as leveling-up Bowling Bulb to aid in the conquest of Big Wave Beach - Day 16.
- Plants that fire projectiles will have their projectiles' appearance changed as they level up.
- Imitater, Marigold, Gold Leaf, and Thyme Warp cannot be upgraded. However, an exploit on 6th October discovered by Redditor FNAFessional allowed Imitater and Gold Leaf to be leveled up.
- Prior to the 5.8.1 update (March 17, 2017), plants were capped at levels 3 to 5.
- Prior to the 6.5.1 update (December 12, 2017), plants were capped at levels 6 to 12.
- When a plant is leveled up, it will play its Zen Garden animation.
- All instant plants up to Far Future includes their animation; all others will have their idle animation reset.
- Bonus seed packets can be assigned to any premium plant present in the game, even if the player does not have it or even if it is not available in the store.
- Bonus seed packets can also be given for Epic Quest plants. However, if you already owned that plant before the 5.7.1 update, you have to complete that plant's Epic Quest in order to receive the seed packets.
- Seed packets from plants that are unlocked in the Player's House and in Ancient Egypt appear in Ancient Egypt piñatas.
- Peashooters are the first max-level plants (level 20) that the player is able to use, but only in the quest "Leveled-up plants are AMAZING!", which is accessed via the Travel Log.
- Missile Toe has the greatest number of statistics that can be upgraded, with a total of 7 statistics.
- The player cannot upgrade plants that have not yet been won or purchased; however, he/she may collect seed packets for them.
- In the 5.7.1 update, although there were Jurassic Marsh quests, 5 gems were given as rewards instead of piñatas. The player also couldn't find them in the store. The Jurassic Marsh piñatas became available in the 5.8.1 update.
- Currently, the Plant upgrade system does not apply to Vasebreaker levels. All of the plants involved remain at their Level 1, with the exception of Cherry Bomb in Vasebreaker Endless.