Curious, can one tissue culture a sugar leaf of a plant that is in week 9 flower? Can one tissue culture a sugar leaf from a freshly harvested branch or a branch cut few hours after harvest? Would this work?
Basically, cuttings from young vegetive shoots is the easiest and most efficient for home growers. Taking cuttings is one of the oldest methods of tissue culture. If your are looking at micro tissue propagation then you will probably need a lab set up. Some here have tried air layering a leaf and got it to root but not grow shoots. That being said, plants are amazing beings, sometimes even experts get surprised, try it and post your outcome here.
The stem cells for tissue culture exist just underneath the epidermis of the stalks. Do you want a dissertation on cannabis tissue culture? I've thought to start, but I have too much to do atm.
I just wanted to know if it's possible on a plant that's done flowering or a branch that's been harvesting a few hours ago
First of all your plant should be a “photo” not “auto”. Some folks have successfully rooted shoots from a plant in flower. It may freak out and take a long time to root then reveg. Never heard about a cut branch hours after harvest. Using a branch that was cut a while ago will more than likely have embolisms. Also the younger the shoots, the better the chances to root. A young green shoot will have a better chance for the meristematic cells surrounding the vascular tubes to differentiate into new rootlets. I mentioned all this so if you try to root a stem from a blooming plant you will have a better chance to have roots. Next time plan ahead and take cuttings before you put it to bloom. 3 strains grafted Bonsai Mom