There are a number of possibilities to obtain healthy cannabis plants. You can grow young plants from seeds, cut small sections from a host (mother plant) or use invitro methods, under microscopic circumstances in a laboratory.
The most common used method is to take cuttings, or clones, from a healthy stock plant, the cannabis mother plant. The mother plant is the nursery for future generations of plants. It is therefore of great importance to be sterile and to have the right climate conditions.
Once the cuttings are harvested from the mother plants, they have the same DNA / genetics as the mother and are basically an exact genetic copy of the mother plant. The cuttings are no more than a little branch with a small leaf, without any roots. As in nature, the plants will undergo a transformation by employing their own stem cells, rearranging them in such manner that rooting will take place. This might be with or without using rooting hormones. Once these clones are dipped into the rooting medium, they will be transplanted in small trays for further development in a complete controlled clone room, where climate is fully adjusted to the requirements of the clones.
If the climate control is of lesser quality and requires more air movement, it is possible to place domes on the trays. During the growth process of the roots, which takes a few days, the light intensity is lower in this room. Once rooting takes place, the plants start to grow. At this time, the plant will start expelling more water through its leaves and it will require more water, more light and more carbon dioxide to enhance photosynthesis. At this stage, the roots are still developing, and the plant keeps growing. Because the roots have to keep up with the transpiration, or evaporation, the light intensity and preferably the light color are adjusted to nurture the plants initial stages. Once the roots are strong enough and the plant starts to really grow, the clones will be transferred from the nursery, or clone room, to a larger pot, or hydroponic medium.