Minecraft wiki entry for Soul_Sand, associated text: Soul sand is used for growing nether wart, a primary base ingredient for many varieties of potions. Nether warts can be placed on soul sand like seeds on farmland and over time they grow through four growth stages (placing the nether wart on soul sand grants the "A Seedy Place" advancement‌[Java Edition only]). Nether warts can grow in any dimension and do not have any light-level requirements. Nether warts can also be placed only in soul sand (and cannot even be placed in soul soil).