Brown seems pretty simple and in fact it is, but sometimes it can be confusing. Harvest Moon brown henna hair dye blends with your brown. The most important thing to identify is : light brown, brown (medium brown) and dark brown. The majority of the time if your on the dark side of brown and you have gray strands, you will need to dye your entire head. Using dark brown will blend it all together. If you have white coming in at the roots, then you can just touch up the roots with a hair dye application brush. Most people need 1 application, however if 24 hours it is not dark enough, just apply it again. You might need to add indigo in with the dark brown to make it darker the next time. If it comes out to dark, then next time use brown instead of dark brown.