text: Semi-permanant color lasts up to 6 weeks. That just means that it will fade off a little bit. You cannot control how much your hair grows.  It grows a 1/2 inch every monthy on average. Therefor, you will always need to color it every 4 to 6 weeks. To keep your hair healthier, I would suggest that you see a professional because it is relaxing and easier, plus everyone can tell if you color your own hair. Trust me. If you keep doing it at home, then do a retouch when needed and on the 2nd time that you would retouch the roots, pull the color to the rest of your hair the last 5 minutes to refresh it. You can use whatever you prefer too-semi or permanant.  I would use permanant to prevent fading. And don't forget a color safe shampoo! Hope this helps!