Sprout, A.K.A. Experiment 509, is an illegal genetic experiment created by Jumba Jookiba. He is designed to rapidly grow into an uncontrollable killer forest of destructive replicas of himself. His one true place is atop the pineapple water tower. He is voiced by Frank Welker.
He was activated when Lilo dropped his pod in a pail of water. Lilo and Stitch ended up catching him after he had grown enormous, deciding to put him in an old water tower that was slated for demolition. However, in the battle between the Leroy army and the experiments at the end of Leroy & Stitch, 509 did not sprout into an uncontrollable forest of destruction like he did in his episode.
Sprout is wild and tends to be aggressive, often trying to bite people when he was still confined in a flower pot. After he rooted into the ground and grew to enormous proportions, he became very dangerous, spreading his vines like weeds to attack victims. However, he apparently calmed down after being uprooted and contained. He also seems to like Lilo.
Sprout is a plant-like experiment with a thick green stem, leaf-like body, eight tentacle-like vines, a purple head shaped like a Venus flytrap, a large mouth with a lizard-like face, little sharp teeth, dark blue pupil-less eyes, three leaves surrounding his head like a frill (one leaf is under his chin while the others are behind his head), and a single antenna on his head.
Sprout can grow much faster than ordinary vegetation. He can also root into the ground and sprout a destructive forest of vicious duplicates. He has burrowing capabilities, and sends out tendrils that grow new heads and act like weeds, but with replicas of Sprout's head. Looks like harmless plant one moment, but suddenly rises up like savage beast and attacks (as stated by Jumba in "Sprout"). He can produce seed pods and launch them into space, where they cling to asteroids. One of these pods landed on the island and grew into a "Sproutling" (509-A) that carried out Sprout's original programming before being neutralized.
Sprout has shown to be skilled in playing the drums.
If the original Sprout's roots are separated from the forest and contained, the rest of the forest will die off. Sprout is also vulnerable to plant-trimming or weed-cutting machines, such as a tractor or lawn mower.
Sprout has made one appearance in the Stitch! anime and was mentioned in another. Though he did not officially appear in the second episode, his son did. It is revealed that Sprout can produce seed pods and launch them into space, where they cling to asteroids. One of these pods landed on the island and grew into a "Sproutling" (509-A) that carried out Sprout's original programming before being neutralized.
- Sprout was first revealed in a DVD bonus feature of Stitch! The Movie in the experiment gallery.
- Sprout is an obvious parody of Audrey II from Little Shop of Horrors.
- Sprout bears a resemblance to the Piranha Plants from the Super Mario Bros. games and Bloomsday from the Wii game Wario Land: Shake It!.
- Sprout's holographic silhouette appeared in both "Amnesio" and "Fibber".
- Sprout's pod color is blue.
- Sprout is described by the experiment computer screen as, "Experiment 509. Primary function: Sprout into an uncontrollable forest of destruction".
- In the battle between the Leroy army and the experiments at the end of Leroy & Stitch, Sprout did not spawn into an uncontrollable forest of destruction like he did in his episode.
- In the English dub of Stitch!, Sprout has a son named Sproutling (a.k.a. Experiment 509-A).