Does shaving the scalp affect hair growth?

Shaving has no effect on scalp growth 

I'm often asked if shaving affects hair growth. The answer is no. Shaving has no effect of the growth properties of the hair follicle and the decisions that are made by the dermal papillae and hair matrix which are deep under the scalp.

Men with genetic hair loss often shave the scalp to reduce the contrast between the thin miniaturizing hairs or vellus hairs and the terminal hairs. Some individuals with alopecia areata also shave for a similar reason. 

But the decision to have is purely cosmetic and has no effects whatsoever on hair growth.