I know exactly what you mean, however I do not know the answer - sadly.
My dad used to. I never listened.
I think if you wanted hair growth it was crescent moon.(opposite to what we'd want when shaving!)
I will write to my (older) sisters and see if they recall...
I have found myself more and more sorry for not listening to my dad - he knew so much and I learned so proportionally little.
I think full moon was the end of the season (stop growth) so that might be it, however - this is a guess. I will ask and try to find an answer.