I think I should have posted this in hair coloring. Oops!! But anyway, I am 42 and my roots are showing up more & more grey. I need a suggestion for covering up my roots to blend in with my natural light brown color. Henna is out of the question!!! Had a bad experience with henna like 4 years ago. Any gentle dyes out there? Semi or permanent?         Thanks :)

Any dye or color will damage your hair.  Henna is the only safe natural"dye",if you want to call it that,that won't damage your hair.  In fact,it can only do good.  Like anything else,some people could be allergic;so do a sample test. Then do  a harvest test.
A site that I get my henna and indigo from that I swear by is Mehandi.com   Catherine who "runs the show" has her Masters in Henna.  Very helpful and knowledgable,that lady is!!
Go snooping around the site,it is very informative.

Any of the chemical coloring processes will damage the hair.  Henna is a vegetable coloring that does not require chemically changing the hair.  Curlgirl's site for Henna is the best from what I have heard.

If you're dead set against henna, then semi- or demi-permanent haircolours are the next best thing.

Semi-permanents (Level 1) contain no ammonia or peroxide and last about a week.

Demi-permanents (Level 2) contain no peroxide and last about a month.

What you want to avoid is permanent (Level 3) haircolour which contains the highest amount of harsh chemicals.

If you're just touching up the roots, it won't be as damaging. You should only have to colour the entirety of your hair maybe once a month. Anyway, HTH. :)

Thanks everybody. I'm gonna try clairol nice n easy root touch up.