Plastic drink cup, RO Water, no additives.
Soaking rockwool in diluted Clonex, General Hydroponics 3 part, vegetation mix, 1/4 strength.
Will soak for 2-3 days, prior to adding the germinated seeds from the cup.
I put the cup of water with the seeds in the furnace room as during the winter this is consistently the warmest area in the apartment.