One method to add different aromas to your herb, and can help to mask the Oder to a certain degree. Take a string and put it threw a needle, draw the needle threw the center of your stem, pulling the string threw the hole, now with the string in the center of the stem, dip the end of the string into extract oil/smell that you want and it will be drawn up the string via whick process into the plant.
Not my thing, but does work. I learned it from a local grower who now lives in Holland and does the whole seed breeding thinggy now, "Grow Doc". He specializes in medical strains.
Adieu