Yes you personal the rockwool as grodan specifies and then transplant and don't water for a few days sometimes several days depending on environment. That forces the roots to seek out water and get established in the hugo. I grow in coco and rockwool and rockwool holds onto alot of water. Even when you think it's dry it's really not. I keep a dry cube nearby to remind myself how light they are dry. And I'll be switching from the hugos to the paragos. They drain easier and are better suited for my setup.