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Miracle-Gro Monster

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Pictured above: Kenneth.
Pictured below: Kenneth. Several meals later.

Lucky you, you just bought a new pet at The Little Shop That Wasn't There Yesterday. But you'd better be sure that you read the care-of manual very carefully. Odds are there is one thing that your pet should never under any circumstances get its hands on, otherwise it'll start growing... and growing... and growing, until it's a 50-Foot Whatever. Before you know it, the military will be shooting at your pet, unaware that all it needs is some Applied Phlebotinum to get back to normal.

This may be a natural part of the creature's biology, or it could be the creature became exposed to Green Rocks.

When a villain does this deliberately, it's Make My Monster Grow.

Quite nearly always a Snowballing Threat.


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    Anime & Manga 
  • Creamy Mami, the Magic Angel: Happens to Nega (a tiny extra-terrestrial cat) when he is infected by Earth's common-cold virus, in the gag episode "The 'atchoo!' of horrors".
  • Moguchan, from an episode of Mirumo de Pon!, a plushie brought to life by Rirumu's magic, grew whenever it ate anything.
  • In the second-to-last episode of Wandaba Style, Michael Hanagata becomes enamored of Sachiko, a tentacle alien that gets bigger when exposed to water. Unfortunately, Michael takes her to play in the ocean...
  • Powerpuff Girls Z has an episode where a duck grows bigger.
  • Love Hina has an episode where a robot turtle grows bigger the more metal it eats.
  • The last episode of FLCL has Mamimi feed a robot dog, which grows.
  • Rage Shenron from Dragon Ball GT grows bigger the more electricity he absorbs.
  • In one episode of Wedding Peach, the Love Angels fight a snow demon that grows every time Angel Salvia cuts it with her sword.
  • Monster Musume: In one chapter, Suu falls into some industrial waste and grows to kaiju size. She turns back to normal by the end of the chapter.

    Comic Books 
  • Disney Ducks Comic Universe: One Donald Duck comic had Donald bringing a special African snail to eat the crab grass on Uncle Scrooge's lawn (which Donald had caused by buying cheap lawn seed). What he didn't realise was that the snail would keep growing as long as it had a steady source of food.

    Fan Works 

    Films — Animation 
  • Phineas and Ferb The Movie: Candace Against the Universe: Super Super Big Doctor's mind controlling plant, Mama, needs carbon dioxide to survive and create mind controlling spores. While in Earth's atmosphere, which is rich with carbon dioxide, it'll actually grow to the size of buildings and come to life, destroying or eating anything it sees.

    Films — Live-Action 
  • The Adventures of Galgameth: Galgameth starts out small enough to fit in Prince Davin's hand and looking like a gold-painted Minya, but the more metal he eats the larger and spikier he becomes.
  • In Honey, I Blew Up the Kid, Wayne Salnski's infant son Adam was accidentally zapped by a growth ray, causing him to slowly increase in size each time he got near an electrical device.note 
  • The Blob (1958): The Blob gets larger the more it eats.
  • Hedorah from Godzilla vs. the Smog Monster grows larger and more powerful with the more toxic waste he eats.
  • Evolution (2001): The aliens react to fire by melding and enlarging, so when the Army decides to napalm-bomb them... they cause one singular cell to rapidly evolve into a simple, gigantic amoeba that wipes out a substantial amount of the military before it's de-evolved due to chemicals in shampoo.
  • The Crites from the Critters film series grow after they eat.
  • In 7 Faces of Dr. Lao, it turns out that Dr. Lao's pet goldfish has this problem if any part of it is exposed to air. When the Mooks of the Big Bad knock over the goldfish's little bowl, it grows... into the Loch Ness Monster.
  • 20 Million Miles to Earth features a wonderful Harryhausen creature that grows uncontrollably because of Earth's oxygen rich atmosphere.
  • The eponymous Kaiju of Pulgasari grows from a tiny figurine size to Godzilla size as he eats more iron. After figuring this out and also realizing that Pulgasari is invincible, the peasant rebels start going out of their way to feed him all the enemy weapons they can get their hands on.

  • The classic children's book A Fish Out of Water involves a boy overfeeding a fish despite the warnings of the pet store owner. The fish begins to grow bigger and bigger, with the boy having to find larger and larger containers to put the fish in.
  • The Monster Blood from the Goosebumps subseries of the same name, along with whoever or whatever eats some, gradually grows bigger.
  • Another Goosebumps story involves an experimental ant farm in which the ants are supposed to be only fed specialized gel caps. When the narrator starts feeding them other foods, they grow into Big Creepy-Crawlies and feed him a gel cap, which shrinks him down to ant size.
  • In the story The Bakers Cat by Joan Aiken, a cat grows larger than the entire town after his owner feeds him yeast.
  • In the Shivers (M. D. Spenser) entry, "Watch 'em Kill", the protagonist is a fan of "Watch 'em Grow" toys. And comes across a bunch of pills from a mysterious store, which morphs into assorted classic movie monsters, ranging from mummies to a werewolf and vampires.
  • In the children's book There's No Such Thing as a Dragon, Billy's mom's denial of the dragon's existence causes it to continually grow larger.

    Live-Action TV 
  • Kitten Kong from The Goodies, who ate feed laced with growth hormone and started growing a lot.

  • The Chicken Heart probably fits here... it's not a WHOLE creature, but it still grows... and grows... and grows... until it is as big as Earth.

    Tabletop Games 
  • Green slime from early editions of Dungeons & Dragons worked like this, dripping onto organic materials and converting them into more slime. Careless adventurers in the early days of role-playing sometimes accidentally caused entire dungeons to fill up with the stuff.
  • The various objects and devices used to stop The Awful Green Things From Outer Space have random effects determined the first time a given type is used. Some types will cause the creatures to shrink or take damage, others have no effect or cause them to grow.



    Video Games 
  • The Maw, from the Xbox Live Arcade game of the same name. He ends up swallowing the entire planet the game took place on.
  • The Munchables for the Wii. Both player characters do this, but shrink back to normal at the end of every level when they...turn everything they ate into orbs.
  • In Wallace & Gromit's Grand Adventures: Fright of the Bumblebees, Wallace makes flowers grow to absurd proportions by a homemade fertilizer he creates out of the active ingredients of body-builder's weight gain formula, then the bees who who are fed pollen from the flowers grow to enormous size, with the queen ending up the size of his truck. One has to wonder if there were any side effects from eating the honey that the bees produced...
  • Metroid:
    • Super Metroid: There isn't much difference when an infant Metroid matures to its larval stage in most cases, but the "baby" Samus spared ends up growing to an unprecedented size, even counting the higher forms as they were depicted in Metroid II: Return of Samus/Metroid: Samus Returns. It also grows differently, as it has no indication of approaching Alpha Metroid status, though later games imply that the true, natural evolution to the Alpha -> Omega Metroid line is only possible on SR-388 (or places that emulate that atmosphere). Metroid: Other M suggests that the baby's enhanced size is because it is a larval queen.
    • While he's already pretty competent in the combat area, Little Birdie from Metroid: Other M later becomes a bizarre, furry scorpion-dinosaur, then a space dragon. Yes, that space dragon.
  • Ratchet & Clank: Going Commando: The Protopet starts out as being about the size of Clank, but after Captain Quark zaps it with device that's intended to render it harmless, it instead grows to roughly the size of Ratchet's Space Plane and becomes the final boss. It's because Quark put the batteries in backwards.
  • A Wii-exclusive powerup in Sonic Colors involves becoming one of these.
  • The titular blob in Tales from Space: About a Blob is one of these. It shrinks back down twice, but on it's third try, it grows bigger than the planet.
  • In the various Ivalice Alliance games, the Carrot is an escaped pet that when the party encounters it turns out to have mutated into a massive malboro, a recurring creature in the Final Fantasy games known for its ability to inflict multiple status ailments.
  • Tasty Planet and all the 50 other similar games.
  • In Fallout 3, the Vault 87 strain of Super Mutants continually increase in size with age, eventually becoming 2-story tall Behemoths.
  • In the intro of Blaster Master, Jason's pet frog Fred grows to enormous size after jumping on a radioactive container, and in the game he becomes the boss of Area 4 and 7.
  • Feed and Grow Fish: Both the player and NPC fish grow in size the more they eat, with a mere guppy being capable of growing large enough to devour a great white shark.
  • One of Fe's quests involves liberating a colossus-sized deer from the Silent Ones. A later Pensieve Flashback reveals that it was once normal-sized, until the Silent Ones overdosed it with Power Crystals.

  • Demon Eater: Saturno gets larger the more demons s/he eats.
  • Mentioned in a Narbonic strip, with a string of flashbacks of Artie coming to Helen with bad news, one of which is "A quantum singularity is swallowing the sealed-off section, and grenades just make it bigger!"

    Web Original 
  • Leak has the main protagonist grow the more rock it eats.
  • Slime Quest has the title slime grow bigger the more things it eats, but it can convert its mass into upgrades.

    Western Animation 
  • The Wow! Wow! Wubbzy! episode "Attack of the 50-Foot Fleegle": Wubbzy's new pet is never supposed to be fed candy, specifically because of this trope.
  • Beebo from The Powerpuff Girls (1998) was designed to be fed only once in his lifetime, but the girls ended up feeding it once each. It ends up eating half the town.
  • A hamster during an Invader Zim episode gets larger and larger the more it eats.
  • Viva PiƱata episode "Confetti-itis" has this happen to most characters in the show.
  • In Lilo & Stitch: The Series, Experiment 586, aka Tank, is a metal eating experiment that grows with every bit of metal he eats.
  • In the Courage the Cowardly Dog episode "Muriel Blows Up", an experimental carrot lands in the farm's yard. When Muriel eats it, she starts growing to gigantic proportions. Unfortunately, the carrot is also designed to explode after growing enough. To get it out of Muriel, Courage goes inside her body and eats the carrot himself, causing him to grow. After it gets out of him, Eustace eats it, causing him to grow, before the carrot eventually explodes. Unfortunately, the episode ends with Courage discovering a whole crop of the carrots in the farm's yard, and Muriel is eating them.
  • Happens to a little alien felon whom Guy Gardner douses with coffee in the Cold Open of one episode of Batman: The Brave and the Bold.
  • Eileen a.k.a. "Birthday Girl" on WordGirl gets bigger (and greener) the greedier she gets.
  • The sponge monster from the My Life as a Teenage Robot episode "Speak No Evil" grew every time it was exposed to water. Unlike most cases, the creature felt great pain every time he grew, but due to only speaking Japanese, was unable to tell anyone.
  • Johnny Test also had a sponge monster that grew when it was exposed to water.
  • VeggieTales:
    • A monster representing a lie Junior Asparagus told keeps getting bigger as Junior has to tell bigger and bigger lies in order to cover up the first lie he made.
    • There was a similar episode in which a "Rumor Weed" grew and eventually took over the town as a rumor spread and became more and more exaggerated.
  • In one Sushi Pack episode, a scientist creates a tiny dinosaur that eats trash. It accidentally gets splashed with chemicals, which makes it grow bit by bit with all the trash it eats. It also somehow gains the ability to turn anything into trash for it to eat.
  • Jimmy Two-Shoes: Yet another fine product from Misery Inc. Useful for a Clingy Jealous Girl needing to break up an alleged date her crush is on.
  • In The Grim Adventures of Billy & Mandy episode "Little Rock of Horrors", a parody of Little Shop of Horrors, Billy discovers an evil meteor that crash-landed in his backyard, which has an appetite for brains, with it growing as it eats all the brains in Endsville. Mandy's brain, however, ended up being too "spicy" for him.
  • Chip 'n Dale: Rescue Rangers:
    • In one episode, Dale adopts an alien dinosaur that appears to play the trope straight at first, before revealing that he is just as intelligent as the main characters. However, he loses intelligence at the same time as he gains size, and it's stated that the ancient dinosaurs were the result of a previous away team succumbing to this fate.
    • In "Fake Me To Your Leader", Zipper is accidentally zapped by Professor Nimnel's growth ray, causing him to slowly grow in size until he's as big as King Kong. The Rangers end up using the ray's shrink setting to get Zipper back to normal.
  • Jackie Chan Adventures had Hak Fu summoning miniature shadowkhan. They failed to prove a threat until he discovered their shadow-eating abilities. It rendered victims comatose and turned them into massive landsharks.
  • My Little Pony: Friendship Is Magic:
  • The Mongolian Fire Fist Demon from the Kung Fu Panda: Legends of Awesomeness episode "Po Fans Out", which gets bigger whenever it gets hit. Which leads to the aesop of the episode as Po only let out the demon so his Fan Club could watch him beat on somebody.
  • A once-off Mad Scientist villain in The Atom Ant Show creates a "Gobbling Glob", a small gelatinous monster (looking something like a Pac-Man ghost) which is only the size of a baseball... but grows bigger and bigger as it eats. And it's ravenously hungry...
  • The Adventure Time episode "Dungeon" has Finn facing the Bucket Knight. He starts out small, but grows huge by pouring a bucket of water over himself.
    Bucket Knight: Just... add... water!
  • In Wakfu, Rubilax grows larger each time he is attacked. Sadlygrove is able to defeat him by attacking him until he sinks into the ground.
  • In the Pilot episode of Rocko's Modern Life, a slime-mold from the refrigerator is like this. It starts out small enough to be carried around by Spunky, but grows to enormous size when dropped into water.
  • One episode of Grossology had Slitherbuddies, tiny adorable genetically modified snakes that were sold as pets...and ended up growing to not-so-cuddly proportions, driving the plot of the episode.
  • Ned's Newt had this as its central premise, though the growth was temporary. The newt could also shape-shift.
  • In Rise of the Teenage Mutant Ninja Turtles, Mrs. Cuddles grows bigger every time someone screams.
  • An episode of TaleSpin has Molly take in a creature called a Yenkara, which grows giant when it gets wet. Fortunately, it's of the Gentle Giant variety.
  • In Teenage Mutant Ninja Turtles (1987) episode "The Case of the Killer Pizzas", Shredder and Baxter Stockman obtain a trio of meatball-like eggs from Dimension X. Upon being exposed to electricity,note  they hatch into miniature Xenomorph Xeroxes. This turns out to be their infantile stage, however, cause once they jump into sewer water, they rapidly grow to their full size.


Video Example(s):


Growth Pill

Using a special pill given to him by his leader to become a giant, Cron, the stranger from the planet Zod, not only breaks out of a cage, but is able to carry out his mission of conquering the planet.

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