Rosemary oil is a great oil for this purpose which is a great scalp and oil treatment. Vitamin E
is another oil that will aid the hair to grow. One of the best ways to care for natural hair is to use good healthy natural products on your hair. I heard this a lot about sleeping on satin pillows or wearing the satin bonnet to bed to avoid having the natural oils absorbed out of your hair, this actually works, however, I don't do it. If you don't sleep on a satin pillow or use the satin bonnet, make sure you use healthy natural good products on your hair to keep it healthy, by doing this on a regular bases will aid you in having healthy hair and edges.
Note: To avoid having your edges pulled out don't have your edges braided tight, or use glue. These are two ways that will definitely take away your edges. When your edges is removed by one of these sources, you may not get them back. Edges like this below can be grown back with proper care