Grafting cannabis onto other plants work.

The only problem is that THC doesn't graft onto the other plant.

So you could graft your favorite weed strain onto a tomato plant and it would work, but only the grafted branch/branches would--or would have the potential to--produce THC.

Hats are up right now about the topic, only because cannabis hasn't been grafted onto every species of plant to test it out, but based on the experiments that have already been conducted in the past and present it is best to assume that it isn't possible simply with breeding or otherwise regular gardening methods-- but in the future may be available when we further develop our hortictulure technology and get more into the genetic code of things