The Stable Mulch (Japanese: ながながこやし Drawn-Out Fertilizer) is a type of item introduced in Generation IV. It is a type of Mulch used to make Berries remain on the plant longer.
In Pokémon Black 2 and White 2, the Stable Mulch can be sold to the Mulch maniac in Mistralton City for 1000.
Makes Berries stay on plant for 150% of usual time before dropping off.
The Stable Mulch serves no practical purpose other than to be sold.