Lazyman
A great idea.  Need to try beet juice and cherry juice for some purples and reds.  Maybe raspberry, blueberry and blackberry too.  

Thanks Lazyman.... believe it or not I've used those before on wood. Believe me they look nice and would on these ribbons as well. 
The problem is that natural dyes for the long term are not colofast. Sure coloring them works and looks nice but eventually will fade. When is hard to determine. They are "fugitive" colors and really the only way to make them last is to use a mordant (metal salt) which you can buy or make and add to your otherwise fugitive dye. The only sample in this collection that is colofast is the Iron Acetate one.