How to keep from being gray hair?

I have had much gray hair since a teenager. I used a liquid or cream for change of hair color after becoming gray hair. I prefer not use it, and think about the way to keep from being gray hair. If you know it, please let me know it.How to keep from being gray hair?
To check graying of hair, mix lemon juice in olive oil, beat till frothy and apply on scalp and wash off after an hour. Premature graying of hair can be postponed by using a strong decotion of black tea and a tablespoon of salt, strain and apply to the roots for 45 minutes and wash with water. Don't shampoo. Check out http://usefulinfo-grayhair.blogspot.com/ for more info on gray hair.How to keep from being gray hair?
the only way to stop gray is keep it dyed then your not really stopping it. all your doing is covering it up.