40mm cubes weigh 5g dry. They are "damp" when they weigh 25-30g, or when they have 20-25ml of water in them.

Please have a look at this photoessay on cloning in rockwool.
Al B. Fuct Reviewed by Al B. Fuct on . New clones cut, how often do I water them?? I just took cuttings and they are placed in 2" rockwool cubes. The cubes are in a dome sitting on 1/2" of perlite on the bottom. I also have a heat pad placed under it. I have been misting the clones about every 6 hrs. or so. I was told to keep it damp but not wet...whatever that means. This is day 3 and they look deep green and are standing up strong. The rockwool is getting a bit dryer, but it stays moist from the perlite so...not sure how to handle the first stages of watering these Rating: 5