Just spray the forth node. . I got 7 seeds out of it. 7.Hey Weff, only the bud I touched with pollen will make seeds if I did it right and no pollen blows around to the rest of the buds. Hence the water spray, to kill any unwanted pollen. The whole rest of the plant will be seedless.
The refractometer I think, I'll be able to see if or how much a plant likes an input or not with it someday.