Soaking: New rockwool contains some residual lime from production, and sometimes some chlorine as well. Soak in pH 5.0 water (no lower, or you will damage the rockwool fibers) for 24 hours. The lime & chlorine will raise the pH of the soak water, but once you've properly soaked & flushed, rockwool will no longer effect your pH. Immediately before use, flush the rockwool with a mild, pH adjusted nutrient solution (about 1/3 strength).

Rockwool moisture: After flushing, give each cube a quick, gentle squeeze (about how you'd affectionally squeeze a kid's hand) to remove 5-10% of the liquid and allow air to enter in its place. Feel how moist that is, and then try to keep it that moist (drip or mist rez solution on it as needed) until the roots have grown out enough to get adequate moisture from your system. If, after your roots are doing their thing, you notice that your rockwool dries out a lot, the humidity in your grow area is probably too low. Keep wetting the rockwool as above, and get your humidity up.

Germinating & Sprouting: Yes, once your seeds crack, make a little hole (about twice as deep as the seed is tall) in the (soaked & flushed) rockwool and put the seed in, pointy end up. Push little bits of rockwool back over the seed gently (don't compact). Then you can keep the cubes in a small container (a Jiffy propagator or a clean plastic margarine tub). Keep them damp with pH adjusted H2O or with the 1/3 strength nute solution, and keep them warm and in the dark - until you see spouts. Then you want them to get light... But don't overdo it. Start with an indirect light source, gradually increase intensity as they harden off. You can wait till the roots poke out to put them in the system, as the small container will keep humidity higher and help keep the rockwool moist, or you can just pop 'em directly into your system if you want to, check the rockwool moisture regularly.
mackSwell Reviewed by mackSwell on . initial rockwool start? Ive been reading up alot on ebb & flow which is what i plan on doing so i know most of the basics now the only thing that i am not sure about is the startup with rockwool cubes. If im wrong please let me know thats why i am asking this. So you germinate the seeds once they crack i place them in rockwool cubes. Then once roots show out the rockwool cubes place them in the system right? now the questions i got is: 1. should i just let rockwool cube soak in ph corrected water for a day or so Rating: 5