- For strategies on how to defeat Plantera, see Guide:Plantera strategies.
"The jungle grows restless..."
After all three Mechanical Bosses have been defeated (only one required in the Console version), one or more Plantera's Bulbs will appear somewhere in the Underground Jungle. Destroying one of these bulbs requires a Pickaxe or a Drill, and upon doing so, Plantera will spawn immediately at that location.
Plantera moves through blocks as well as using long vines to grapple foreground blocks in order to move. Its grapples cause damage on contact, and can be killed individually, but only its main body needs to be killed in order to defeat Plantera.
 First stage
Plantera creeps after the player, firing seeds and flower petal projectiles. These fire more rapidly as Plantera takes more damage. Plantera also begins to spit large, bouncing spiked balls after taking a certain amount of damage.
 Second stage
Once Plantera is brought down to half its original health, it changes to its second form, with its pink bud falling away to reveal a thorn-filled mouth. In this form, Plantera moves quicker, and primarily attempts to make physical contact rather than fire ranged attacks.
- It sprouts mouths that are attached via additional vines (called "Plantera's Tentacles").
- It begins releasing floating pink spore projectiles that drift toward the player, similar to the spores released by the Giant Fungi Bulb.
 Enraged stage
Plantera only becomes "enraged" if it follows the player out of the Underground Jungle, for instance to the surface. This causes it to gain significantly more damage and movement speed, and will attempt to remain directly on top of the player, causing constant damage.
 Attack types
- Seeds (first stage): Similar to the stingers of the Hornets. They do not travel through blocks.
- Thorn Balls: Spiky balls similar to the Spike Ball weapon. They linger on the ground and deal around 50 damage. These fall through platforms, but also bounce very high.
- Hooks: The ends of Plantera's tentacles, which cling to surfaces and deal damage on contact. They can be killed individually.
- Biters (second stage): Gnawing minions on "leashes", akin to smaller versions of The Hungry. They get in the way of the player's attacks, making piercing weapons more valuable. Fairly weak and easily killed.
- Spores (second stage): Similar to the Fungi Spores fired by the Giant Fungi Bulb. Travels through blocks. Easily destroyed, but deal high damage if touched.
The Temple Key allows access to the Lihzahrd Temple and Golem Boss, who drops Beetle Husk for crafting Beetle armor. In addition, the Temple Key can be combined with Biome Key Molds to craft keys for access to Biome Chests.
The Cyborg NPC becomes available, and the Truffle begins selling the Autohammer, used to craft Shroomite Bars for Shroomite armor and other endgame items. The Traveling Merchant will begin selling the Pulse Bow.
A message saying "Screams are echoing from the dungeon" will appear, as new, more difficult enemy types will begin to spawn in the Dungeon, which drop new weapons, accessories, and other useful items. Dungeon Spirits will begin to appear when Dungeon enemies are slain, which drop Ectoplasm, a new crafting material that offers access to the Pumpkin Moon and Frost Moon events, as well as the Spectre armor and tool sets.
Hardmode Crimson, Corruption, and Hallow spread will be slowed.
- If Plantera is currently summoned and you break another bulb, a second Plantera will not be summoned, though the bulb will be destroyed.
- If Plantera has no surfaces to latch onto, the body of Plantera will slowly float off, going up into the space portion of the map, or until it hits a space where it can latch onto again. This can cause the loot from the boss to be unreachable in some cases.
- If the player strays too far away from Plantera, it will despawn.
- If the player stands inside Plantera in its second form, the Plantera's Tentacles will not target them.
- Excavate a sizable area to allow easier dodging before summoning Plantera.
- Plantera's Bulb can spawn in player-made Jungle Biomes, which can provide a slightly easier way to fight Plantera.
- Line up 2 teleporters ~50 blocks away from each other in two small separate rooms with a tiny hole. When Plantera is summoned, fire at it using a Megashark or Clockwork Assault Rifle. When it gets too close, teleport to the other room.
- Narrow Passages slow Plantera as it takes more time for it to grip the surrounding terrain. Use of the Death Sickle in the narrow passages will result in up to 3,000 max damage in a 30-40 tile tunnel.
- If you have already beaten the Golem, the Stynger is very effective. Dart Traps or Super Dart Traps can be useful. Golden Shower, Ichor Bullets or Ichor Arrows may be useful as the debuff they inflict lowers its defense. The Bunny Cannon and Flairon are also effective.
- In multiplayer, build a house with a bed near Plantera's Bulb. Make all players spawn at the bed, so you will be sure to kill it, as Plantera does not despawn unless all players die and spawn in other places.
- The name "Plantera" is a word play of the American metal band Pantera, which is Redigit's girlfriend's favorite band. Plantera drops "The Axe", which looks similar to the Washburn and Dean electric guitars often used by late Pantera guitarist Dimebag Darrell. Its boss music also features heavy electric guitar use.
- This boss bears a resemblance to Kalle Demos from The Legend Of Zelda: The Wind Waker, as well as Biollante from the Godzilla movies. Both are giant flower creatures who eventually transform into a much more dangerous form with gaping, tooth-filled mouths. It also resembles Audrey 2, the antagonist in Little Shop of Horrors.
- In Swedish, the word plantera means "to plant".
- As the console 1.2 update, the new saving icon is one of the spiked ball that Plantera shoots. Prior to this update, the Thorn Chakram was used as icon to save.
- 1.2.4: Fixed bug where "The jungle grows restless" message would appear before you have beat all 3 Mech Bosses.
- Plantera is no longer needed for solar eclipses.
- Its speed has been reduced in both of its forms.
- Plantera now enrages when taken out of the Jungle or to the surface.
- When killed for the first time the message is now "Screams are echoing from the dungeon..."
- 188.8.131.52: When killed for the first time the message "Screams are coming from the dungeon" will appear.
- Fixed a problem that defeating plantera would force serverside characters.
- Solar Eclipses now only happen after Plantera has been defeated.
- Plantera now must be defeated to allow Hardmode dungeon enemies to spawn.
- Hardmode Crimson, Corruption, and Hallow spread is now slowed after killing Plantera instead of any Mechanical Boss.
- 1.2: Introduced.