letting gray grow out

I have medium to long hair which I dye brown. I love the silver coming in at the roots and would like to let it grow out. How can I do this without looking like a nut for a year.  I don't want to chop it all off, or do I have to?  Has anyone ever bleached it platinum while waiting, then it will blend?

any input please?

Well I'm doing what you suggest and am just letting the white come through naturally.   The white is about five inches long and the old dyed brown stuff is about 6 inches long.  Sounds awful and in some lights it looks awful as well.  But a lot of the time it looks fairly ok and I'm feeling strong enough to brazen it out.  I think in a few more months I will be really glad that I did.  I've been thinking really hard about hair color this year and have come to the conclusion that we all let fashion and what other people think worry us too much.  Do whatever you want to do!!

As someone with premature gray hair, I was always being urged to color it.  At one point I tried a very light blonde.  I didn't especially like the color, and I REALLY didn't like how my hair felt after all that processing.  So I started with getting low lights, going a little darker each time and eventually eliminating the highlights.  When it was able to grow out without my looking like a bomb popsicle, I let it grow until the non-colored part was about two inches long.  Then I cut it all off in a supershort style. 

I haven't colored my hair in about three years, and I am much happier. 

I think the grey looks more aging because it contrasts with the dyed hair.  If you can bear to let it just grow out, I think you might find it is less aging.  That's what happened to me anyway.  Good luck.