Double White Cheese Males-In & Outdoor

This will be a first time try with Double White Cheese and also doing hydroponics outdoors. I usually run RDWC indoors. DWC seems very vigorous. I soaked the 6 seeds for less than 24 hours in straight tap water at about a pH of 7.0. Put them in paper towels and germinated them in zip lock bags. All 6 germinated. Added the seeds with sprouted tap roots to rapid rooter cubes soaked in water with a small amount of vitamino. Put seedlings in a seed tray with high dome under a 18W full spectrum LED. 4 of the 6 developed roots out of the bottom of the root cubes, protruding out of the bottom of the seed tray by the end of week 1. 1 seedling died. 1 seedling clung to life and suffered what looked like deficiency or burn. It is noticeably smaller than the others.