Metal Rockers Korn -- GROWING CORN While Recording Album

Korn has been hard at work the past few months using their indoor hydroponics setup to grow a few pounds ... of CORN!!!

Turns out the guys got real health conscious while recording their new album "The Paradigm Shift" -- and bought a micro-indoor farm to grow corn and other vegetables inside of the studio so they wouldn't have to buy from a store (photo below).

"TPS" will be a historic album when it's released in October since it marks the return of co-founding guitar player Brian "Head" Welch ... who left the band in 2005 for religious reasons.