It's a busy day for Rupert and Bill — they discover the Professor has developed a growth formula that can make apples as big as a truck the same day they decide they want to learn how to carve topiary like Rupert's dad. When their attempts to "improve" Mr. Bear's latest sculpture leave them with a bush too tiny to be turned into anything more than a hedgehog, they try to use the Professor's formula to reverse the damage. Thanks to Bill's overzealous application, the result is a giant, sentient hedgehog made of leaves and branches rampaging throughout Nutwood. Their only hope for stopping it is Rupert's connection with the Autumn Elves.
This episode provides examples of:
- Art Initiates Life: A shrub carved into the shape of a hedgehog + a super plant growth serum = a sentient shrub that behaves like a real hedgehog.
- Chew-Out Fake-Out: When Mr. Bear discovers the hedgehog Rupert made out of his camel, Rupert expects to be in big trouble for ruining his hard work. His father, however, is mostly just impressed with how realistic his son's first attempt at topiary turned out.
- Disaster Dominoes:: Bill tries to make an unnecessary adjustment to Mr. Bear's camel topiary. Every attempt by the boys to fix a mistake turns into a disaster, requiring further adjustments, which make it worse, until there's barely any shrub left.
- The Friends Who Never Hang: Constable Growler insists the boys stay behind while he and the Professor try to stop the hedgehog. It's rare you see any of Rupert's friends working together without him, let alone 2 of his adult friends.
- Gondor Calls for Aid: Rupert turns to his old friends the Autumn Elves for help stopping the hedgehog using the potion they use to stop plants from growing in fall and winter.
- Luck-Based Search Technique: Rupert and Bill need to find the tree that leads to the Autumn Elves' home. Bill gives up and kicks a tree in frustration, which opens to reveal...
- Never My Fault: Bill spends the entire episode telling everyone Rupert was responsible for each and every thing he himself did.
- Planimal: The living hedgehog shrub.
- Two Lines, No Waiting: Rupert's and Bill's attempts to find the Autumn Elves and get the potion to the hedgehog occur while Constable Growler and the Professor are chasing the hedgehog on their own.
- Vitriolic Best Friends: Rupert and Bill get on each other's nerves and argue more than in any other episode.
