Shrinking Solution / Shrinking Potion - Harry Potter Lexicon

Effect: Makes things shrink in size, apparently reversing the aging process as well.

•  Harry had to write a particularly nasty essay on Shrinking Potions as one of his holiday assignments for Potions the summer before his third year (PA1).
• Administered to Trevor in Potions, the toad didn’t just become smaller but turned into a tadpole; this was the expected effect (PA7).
• Shrinking Solution has always been popular to use with livestock, enabling a farmer to carry a herd of pigs in his pocket (BoP)

Ingredients

Prisoner of Azkaban Version:

• Daisy Roots
• Abyssinian Shrivelfigs
• Caterpillars
• Rat Spleen
• Leech Juice

Pottermore, Wonderbook Book of Potions, and Video Game additions:

• Infusion of Wormwood
• Cowbane Essence

Preparation

Prisoner of Azkaban Version

• chopped daisy roots
• skinned shrivelfig
• sliced caterpillars
• one rat spleen
• dash of leech juice

• Apparently it's important that the daisy roots be chopped evenly before they're used (PA7).
• Adding too many rat spleens or too much leech juice can cause the potion to turn orange instead of the bright acid green it's supposed to be; making errors in the potion can cause the mixture to become poisonous (PA7).
• Professor Snape tells Neville Longbottom there should be only a "dash" of leech juice.

Pottermore Version: Part One

• Shrivelfigs
• Daisy Roots
• Hairy Caterpillars

Crush Two Shrivelfigs in Mortar. Add 5 measures of juice to the cauldron. Stir 6 times, clockwise. Heat on low for 25 seconds. Add 4 measures daisy roots. Crush 5 Hairy Caterpillars in the mortar. Add them to the cauldron. Wave your wand and leave to brew. Wave your wand again to finish.

Pottermore Version: Part Two

•  Infusion of Wormwood
• Leeches
• Rat Spleen
• Cowbane Essence

Add 3 measures Wormwood to cauldron. Stir 10 times, clockwise. Crush 4 Leeches in mortar. Add 3 measures Leech Juice to cauldron. Stir 6 times, anti-clockwise. Crush one Rat Spleen into a paste in the mortar. Add 2 measures of Rat Spleen paste into cauldron. Add 3 measures Cowbane Essence to cauldron. Stir 5 times, anti-clockwise. Heat on high for 10 seconds, then wave wand. Leave to brew. Wave wand again to finish.

Wonderbook: Book of Potions Version Source: Video

The Shrivelfigs are juiced with a hammer. The Wormwood and one rat spleen are shaken before adding. The Cowbane isn't measured, but added as a "splash."

Half-Blood Prince Video Game Version Source: Video

The purple Shrivelfig bottle must be shaken before pouring, which produces dark gray smoke from the cauldron. Several pours are needed before the potion turns green. Four rat spleens are shaken and used, instead of one. Five leeches are added directly to the cauldron.

History and Notes

Zygmunt Budge told the story of wizard Samuel Plunkett, who was persecuted by a village so in revenge he dumped Shrinking Solution into their well on his birthday. Then he chased the little villagers around trying to stomp them with hobnail boots (BoP).

Budge himself once spilled a Shrinking Potion on the grass causing a flock of sheep to shrink to "lambs the size of wooly mice," which he used as ear warmers on cold days (BoP).