Lilo activates a plant-like experiment to enter it in an orchid competition at the fair despite Jumba warning her not to. The experiment then grows out of control and Lilo and Stitch must stop it.
Lilo is seen writing to her pen pal, a soldier stationed at Camp Pendleton, about the various adventures she's had since meeting Stitch. When she goes to the post office to send the letter, she stumbles upon an experiment pod lying on the ground.note She takes it home to Jumba, who reveals it to be X-509, a plant-like experiment designed to cause havoc and destruction. Lilo wants to activate it to find its one true place, but Jumba locks the pod in a drawer, explaining that a plant cannot be reasoned with, and activating it will do nothing but cause massive destruction. Lilo is disappointed, but unwilling to go against Jumba's wishes.
At hula class, the students examine a poster for the upcoming Kokaua Town fair, and Mertle is confident her orchid will win first prize in a competition, but Lilo claims to have an even better orchid that will win (it's black... with polka-dots!). They end up making a bet, that the winner will get exclusive rights to the island's best beach for a whole week.
As Lilo ponders how she's going to grow an award-winning orchid overnight, Stitch is looking at the town fair's poster and is interested in the rodeo competition. He heads home, reads about cowboys in a picture book, then assembles a fully-functioning mechanical bull out of common household parts. Lilo asks Pleakley to help her grow an orchid, but he is too busy growing a giant "Pi-Normous" pineapple (with the help of Jumba's evil genius fertilizer) for the home-grown fruits and vegetables competition. Lilo asks Nani for help as well, but she says that an orchid can't be grown in just one day and that she should have planned ahead weeks ago. Frustrated, she storms off with Stitch, who is still pretending to be a cowboy.
Lilo realizes that there is a way to grow a plant really fast, remembering that 509's experiment pod is still locked in Jumba's desk drawer. Lilo sneaks into Jumba's bedroom that night and convinces Stitch that the experiment is good. (After all, the best stuff is what gets locked up!) He reluctantly picks the lock with his claw, and Lilo takes the pod along with some of Jumba's special fertilizer. She activates 509 and pours an entire gallon of Jumba's fertilizer on it so it can grow overnight.
The next morning, she wakes up to find that 509 has quite grown, and it looks great for the competition at the fair. Meanwhile, Stitch is dressed in full cowboy garb, complete with lasso, also ready to take on the fair's rodeo competition. As everyone heads to the town fair, it turns out that Stitch has only one other competitor — Zach Makeli, the five-time champion of the rodeo. Meanwhile, after Lilo sets her "orchid" on the competition table, Mertle sneaks up to get a good look at it. However, 509 hisses at Mertle and grabs her arm with a leaf, causing her to back away and knock the plant onto the ground, breaking its pot. It sets its roots in the ground and slowly begins to grow...
Pleakley's Pi-Normous Pineapplenote is about to win a blue ribbon, but 509 (now much larger) sprouts from inside the giant pineapple, destroying it completely. Meanwhile, at Stitch's rodeo competition, Zach scores a near-perfect 99 points bull-riding, beating his own record. Stitch (entering the competition as "The Stranger") is still determined to win, however, and almost wins before large vines sprout directly below him, knocking him from the bull. Each vine, stretching taller than the nearby bleachers, has its own purple snapping head, and they begin to attack Stitch.
As Lilo realizes the horror she's unleashed upon the fair, Stitch gets captured by vines, but cuts himself free using his extra two hands when Lilo tosses him a weed whacker from a nearby lawn care exhibit. The duo quickly climb up to the top of the town's pineapple-shaped water tower, and Lilo laments that if only she hadn't disobeyed Jumba and stolen the experiment pod just to beat Mertle at a competition, none of this would be happening. She then notices that 509 is one giant plant where the orchid competition was, and that the rest of the heads are simply stemming from the original. If Lilo and Stitch can contain 509's roots in some sort of massive container, they can stop the spread. Stitch suddenly seems to have a plan and jumps off the water tower, riding a lawnmower with a yeehaw.
Meanwhile, Nani is relaxing at home watching some light television. And by light television, we mean breaking news about the chaos and destruction happening at the town fair. She calls in Jumba and demands he explain the obvious experiment on the loose. He realizes what Lilo had done but is unable to help.
As Lilo begins to get wrapped up in vines atop the water tower, Stitch is still valiantly charging toward 509 in an attempt to contain its roots. Suddenly, Zach (the other cowboy from before, remember?) ties a lasso around 509's mouth and tosses the rope to Stitch, who ties the end of it to his lawnmower and begins towing the massive plant behind him. Since the main plant has been uprooted, the vines constricting Lilo dry up and break off, alongside many of the giant plant heads. Stitch drags 509 up the pineapple-shaped water tower, cuts a giant hole in it, and contains the plant's roots inside.
The sun begins to set as many civilians gawk at the giant hissing plant now living inside the water tower. Lilo comments that while it may not be its one true place, it's just about the only place it could go. The fair's judges realize that the giant plant was an entry in the orchid competition and give Lilo a blue ribbon, while Zach admits that if it hadn't been for the plant, Stitch would have won the rodeo fair and square. As he looks at his shiny new champion's belt, Lilo feels guilty and gives the blue ribbon to Mertle, who actually deserved to win first place.
Nani arrives at the fair to make sure Lilo is okay, then grounds her for a week for stealing the experiment. However, Nani says that if they plan for next year, they can grow real orchids and have a fair shot at that year's town fair. The ʻohana, safe and whole again, ride — err, walk — off into the sunset.
The experiment of the episode:
- Sprout (X-509): A Venus flytrap-like experiment who is designed to grow into an uncontrollable forest of destruction.
This episode contains examples of:
- An Aesop: Always play fair and take your losses gracefully.
- Cheaters Never Prosper: Subverted; Lilo won the orchid contest with Sprout after all the chaos was over. However, she realizes that she didn't win fair and square since she wasn't even close to prepared for the competition, and it's also her fault for letting Sprout grow out of control (which also prevented Stitch from winning the rodeo competition and destroyed Pleakley's giant pineapple that would have won the pineapple competition). Thus, she relinquishes the blue ribbon and her bet to Mertle and also accepts being grounded by Nani for a week.
- Chekhov's Gun: The technique of potting certain plants in a water pot without soil is later used to plant Sprout in the water tower so his roots are powerless to grow more Sprouts.
- Deadline News: When Nani and Jumba see a live news report on TV about his experiment destroying the fair, we hear a female reporter reporting on it, and she screams as it's implied she was eaten alive by Sprout. Interestingly, after she gets eaten no one seems at all phased by this and no one mentions her again.
- "Shaggy Dog" Story: Pleakley had been working hard to grow his "Pinormous" pineapple for some time and he believes it would revolutionize the pineapple industry after he wins the pineapple competition at the fair. It seemed like he was easily going to win until 509 sprouts from the pineapple as Pleakley was being judged, destroying it and Pleakley's chances of victory in the process.
- What You Are in the Dark: Stitch's competitor could've taken the trophy since Sprout disrupted Stitch's place in the competition. But instead, he honors that Stitch is the winner and gives him the prize. This inspires Lilo to honor that without Sprout, Mertle is the true winner.
- You Are Grounded!: Lilo is grounded for a week for ignoring Jumba's warnings about the day's experiment. Lilo actually would have accepted being grounded for a month, but Nani gives her a lighter sentence for having learned her lesson.
