Hair transplantation is the transplantation of skin with a hair follicle to a recipient area. In skin transplantation the scars need to heal, and that takes about 21 days.
Waiting 1 more week after the 21 days is safer. After 1 month, there is no problem in blow drying the grafted area.
In order to blow dry the hair, ideally, the hair in the transplanted area is long. If the patient had a density enhancing hair transplant, it is all right to blow dry hair or resume hair straightening after one month.
When blow drying burns might occur in the area due to numbness. Because the patient feels numbness, it is best if the blow drying is done at a distance from the skin.