Not sure what you mean by tertiary growth, but if you are referring to branches on branches on branches i get it. First branch, off that comes secondary growth, and off that tertiary? I dont keep it so defined. I just try to remove what isnt helping the plant do what i want it to. I remove the lowest 25%-30% of all growth on the plant, after that i only take leaves that inhibit light and airflow, i keep as many budsites or growth tips exposed as possible and will only remove what doesnt get adequate light and airflow.