I have only fixed a stem and not a main stem but what I did was make a cast around the fracture, if it is broken right off I do not know what to do. If you are interested in trying what I do know just let me know. If it is not broken right off do something and start more silica additive. Heres what I did I used yellow masking tape and wrapped up the fracture, use a stick or toothpick and tape the toothpick over the masking tape you just taped up. The whole idea is just support the break. Then it should heal itself and add more silica to strengthen your stems. Hope it helps.Well good morning waking up to mixed feelings put my thoughts on here about my grow try to get some advice I'm thinking that I might have hurt my plant but nobody seems to notice my post nobody seems to say anything nobody seems to give a shit! Adios amigos I was really hoping somebody would have pitched in on that and gave me some advice because I think I might have done a little snap at the base where it needs to Roots but I see new root growth coming about the stem but it don't matter ain't nobody help on here no more like they used to