Absolutely no nutes, if they have white coming out then they're fine.. Let the cubes get just damp and make sure its pressed snug against seeds, and quit opening it up to look at them.i mean rock wool plugs been ph balanced and ppm is only 250. been thinking they might need more nutes to start but dont want to burn them. like i said they have cracked little white coming out but not at the rate you would think.