How do you make your hair darker without using dye or other products?

I have heard that the following common items are able to make your hair a few shades darker. * cooled brewed coffee * strong black tea * henna * shampoo designed for brunettes The Shampoo has different ingredients to enhance brown hair. If you use this shampoo then I am told that your hair will darken a few shades. All the other bullets are simple: you soak it in a hot water then cool, strain the water and soak you hair for 15 min. Rinse with Clear water.