Cannabis tissue culture is not easy. When large-scale legal Cannabis cultivation started the potential of using tissue culture was recognized early on. Tissue culture was already an established method of mass propagation in many crops, like ornamental plants, fruits, and vegetables. It turned out that protocols for other plants did not work for Cannabis. Most commercial Cannabis tissue culture laboratories over-promised and under-delivered. Cultivators can buy various do-it-yourself kits and premixed media formulations. We have tried those, and none worked as advertised.
Tissue culture is a term used for any method of propagation that involves incorporating a sterile phase. This includes growing plants from microscopic meristems, callus, node sections, and entire shoot tips. Most images on the web show plants in culture vessels that have started as shoot tips or stem sections including a node. Viruses, viroids, endophytic fungi, and even burrowing pests like Russet mites can persist under these conditions and be passed on. When you browse websites and posts from tissue culture laboratories, look for pictures of the process they use. Do they back up the claims? What you see is what you get.
Techniques, such as mass propagation through callus, cryo-preservation, slow growth culture, storage as artificial seeds, and true meristem culture work for other crops but currently have little practical value for Cannabis. This should change when restrictions of Cannabis Research in academic and commercial institutions end.
Our approach to tissue culture starts with small cuts (explants) that contain axillary or apical meristems. These contain little non-meristematic tissue but still regenerate efficiently. Most infections and infestations cannot pass through, and the procedure requires less labor and time than other methods. We do not use anti-fungal agents in our culture media to avoid missing infections that were not removed by surface sterilization. Antiviral treatments can be included in the protocol as needed for remediating severe infections.