100% success with Rockwool cubes and tap water, no cloning gel. Don't let the cube dry out, don't keep it fully saturated after day 1.
Do you have a picture of your setup?
I don't do anything fancy. I literally take a cut and put it in a 2x2 cube. Submerge the whole cube and cut in water for like a minute. Then I place on a plate or prop tray on the floor under the same grow lights that are growing my autos. It's on the floor so it's plenty far from the power of the light. That's all I do.
This is the type of thing Im looking for. I dont want something elaborate.
I usually take a clone when I top. The tops clone nicely. Other than that 3 or 4 inches long, try to stay away from woody parts of the plant, soft green tissue is best. Remove any branches on the cut and just keep 2 or 3 fan leaves and the top if it's a lower cut. If it's a top you can keep a Few branches. After a week of just water start giving them a very week feed. Like ⅕ strength vs what you would feed in late veg and start ph adjusting your water.
