I clone in rockwool, and don't have any problems whatsoever.
I don't have any hard and fast "rules" I follow or anything, just keep it simple. I don't use any magic potions or hormones. Here's my procedure, and since you're new to rockwool, I'll start with it's preparation (which is vital, and where a lot of mistakes are made).
I begin by soaking my 1.5" cubes in the following solution for at least 12 hours:
- 1 gal tap water (70-100 ppm)
- 1 ml Dyna
BLOOM (3-12-6)
- PH to 4.8 - 5.0
Usually twice a month, city water gets treated and comes out of the tap at 150-200 ppm. When this happens I use R/O instead, and add 100 ppm
Cal-Mag.
Once the cubes have soaked for at least 12 hours, I pour off the solution and desaturate the cubes. It is important not to squeeze the cubes even a little. RW crushes easily, and every squeeze collapses vital air pockets. To remove excess moisture, cup the cube in your fingers, and "fling" it. The same gravity that keeps it planted against your fingers forces excess moisture out without damaging the cubes internal structure. Do this until they no longer drip.
Now the cuttings. I think people get too wrapped up in how many nodes to leave, minimum and maximum sizes, special angles to cut with surgical scalpels, magic cloning potions, etc... I ignore 100% of that. I simple look at the plant, and visualize it's growing limbs as new plants growing out of RW cubes. I usually have something in mind for how I want my future plants structure to be, and use that to guide my selection. When I find a limb that suits my preference at the time, I grab my trimming shears and snip it off the plant at it's base. If the first node isn't at least 2" or so from the cut, I snip those leaves off.
Using a blade of my shears, I scrape off the outer layer around the bottom 3/4" or so of the stem. Just a few random scrapes is all, I don't get it all, usually just 3 or 4 swipes to remove a few strips. Now I place these cuttings in my prepared cubes by dropping them in the holes in the cubes until they bottom out, then forcing them another 1/4" to 1/2" to firmly seat them in the cubes.
Finally, I mist the interior of a humidity dome and the new cuttings themselves. Cover with the dome, vents all the way closed. In the winter I put them on a heat mat to maintain sufficient temps. For 5 days I keep all vents closed, and under a T-8 shop light (T-5 are a bit too much for unrooted cuttings). I remove the dome once per day to mist the cuttings and exchange air. RH is 100% and temps around 85 F for this period. After the first 5 days, I begin to open the vents on the dome, a little more each day, slowly acclimating them to the RH in my veg area, which ranges from 70%-85%. Usually by day 10 - 12, they're rooted and ready for more light and a decent meal.
Cannabis is a resilient plant. Don't mess with it too much, and it'll do it's thing. Don't open that dome more than once per day for the first week, and don't mist with tap water. It's not going to kill the cutting, but the deposits on the leaves will interfere with it's ability to breathe and slow rooting considerably (week or more in my experience).
I grow in hydro, and continue to feed new clones bloom nutes for a week into veg. Inevitably, the cloning process results in purpling of stems and yellowing of leaves. Bloom addresses the immediate needs of newly rooted cuttings much more directly than a veg line at this time. Specifically, Dyna is one of the cheapest and simplest to use, despite being almost annoyingly effective.
Good luck!
