We have some good things to mentions as well as some not so good things.
I’ll start with the good. The four plants that are growing in the rockwool look pretty healthy, although some more than others. Three of the four have roots growing all the way through the rockwool and into the nutrient solution. The plant who’s roots have not grown down to the nutrient solution definitely looks less healthy than the others (its leaves are slightly wilted).
Now the not so good. As you can see, the plant in the upper left cup within the picture–the one growing in Perlite–has basically died. We now understand that the Perlite was not providing a moist enough environment for the plant, which didn’t even allow the roots start growing. Also, the three other cups full of rockwool have not produced any plant growth. As of now, it’s too late to replant anything, so we’ll leave the system as it is and continue showering our attention on the three healthiest plants.