The fact that the plant from where you are getting cuttings is growing in soil will have no effect if you want to grow the clones/cuttings in coco. For ease of cultivation, I would be getting rockwool cubes to plant the cuttings in to, however, if the clones are already growing in soil and you want to plant the cuttings with their soil into your coco system, there should be no problems what-so-ever. In fact, your coco would get a microbial boost from the soil. Any soil started cutting should not suffer from nutrient/water build up, as these will just be "sucked up" into the surrounding coco anyhow, coco being quite "sponge" like. Hope this helps,.... Organoman.