I use rockwool cubes in dome trays. Sometimes I use 1 1/2", sometimes 2". I dip em in clonex gel. Here's my deal:
I soak the cubes in a bucket of water (pH 5.8ish, as rockwool is naturally a little high, and so should initially be soaked in kinda lower pH water), along with some B vitamin and if I'm feelin hippy dippy some good compost tea. The cubes soak at least a half hour but less than 2 hrs.
Snips are taken. I like to take em all at once from a single strain. I'll cut em extra long and let em soak in some dilute veg solution til I'm ready to use em, but water would be fine.
The cubes are laid in a tray. One at a time, I take the snips out of whatever they're soaking in and trim them down to about 6". The cut is always an angled one, so there's a point at the bottom of my clone. I don't spend time admiring it; I IMMEDIATELY dip it into my cloning gel, which prevents air bubbles and any other horrors from finding their way into the stem. Then I cut off any excess leaves (they don't need many) and trim off half or so of the remaining ones. It aids aspiration and keeps the leaves from sticking all over each other while they're in the dome. The clone now gets poked into a rockwool cube. They come with holes already in em, but I prefer to poke clones into the rockwool beside the hole, making my own. They sit snugger that way.
If it's a real old, woody snip I'm dealing with, I'll slice the sides of the stem from about 1" up the stem down to the bottom before dipping it in cloning/rooting stuff. Helps the stuff soak in.
The dome goes over the tray, and yes, it is vented, always. And yes, there must be a dome involved. The clones get 18-24 hours of fluorescent light a day. Once or twice a day for the next 7-12 days, the dome is removed and excess moisure is wiped off with a paper towel or something. Ususally, about the same time that I notice I don't have to wipe the dome anymore, the roots have popped out the bottoms of most of the cubes and they're ready for the dome to be removed.
They're good in the tray for weeks and weeks but it's nicer to transplant them into something as soon as the roots have popped.
Remove the ones that took longer to root than the others. Weed out the weak!
Also, some strains are tougher to clone than others. Some just plain don't like it. So don't be butt hurt if you find a plant that seems virtually impossible to clone; they're out there.
This method has not failed me yet. I average 90% success rate on a rough day with it. It's not as complicated as it sounds, if it sounds that way at all...I'm just tryin to go into minute detail so we understand each other.
Good luck!
