When you buy henna, make sure that you get the original product. The original product is a leaf. It is dried and ground into small bits before it is packed. When you mix it with water, it will look green. However after you apply it to your hair and leave it to dry for at least an hour before washing it off, the resulting dye is a dark brown.I would consider trying a henna. I don't know how well it would take on the blond, but I imagine it would take really well. Henna is much more gentle to your hair then commercial hair dye.