A transient numerical simulation of the temperature field distribution in a conventional resistively heated SiC PVT growth reactor revealed that the unintended seeding substrate sublimation typically exists during the furnace heat up stage. Consequently, this would lead to the seeding surface graphitization due to nonstoichiometry of SiC evaporation. Suppression of the seeding surface graphitization requires significant reduction of the furnace heat up time. An optimal elevation of the argon partial pressure and seeding substrate temperature during the heat up stage would also promote repression of the seed graphitization.