TwinLolly
DH uses 1 Tbs or 2 with apple cider vinegar in a glass of water and uses it on his scalp after rinsing off shampoo. He leaves it on for a minute or two, like conditioner, and rinses it out thoroughly. He might smell likee fish and chips for a bit but once his hair is dry, it doesn't smell. It has really helped his dandruff tremendously.
My mum used to rinse her hair in vinegar, too. Something I used to do was rinse my hair in freezing cold water after washing ( I’m sure it helped it to grow, too) but I’ve chickened out of that recently!