Slave gardens: metaphorical.
N. Korea a slave garden where the cabal "grow" the "crops" for their sacrifices/depraved acts.
Remember, N. Korea has the three generation rule. If someone commits a crime their family is also imprisoned and three generations afterwards are forced to remain in the camp.
I'm guessing the children born in the camp are used for these sick acts.
Look at the accounts of escaped/survived N. Korean prisoners. It makes a lot of sense now.