I am sad to say I never saw new growth with the castor oil -- just thicker, glossier (more moisturized). I used the coconut oil with it to make it easier to apply. Castor oil is very thick, and can pull hair out during application.
It did stop falling out but only for a while, then started again. I quit the castor oil mix because of the hair loss during application. Was too scared to continue.
Ran out of nettle, but mine was the leaf, not the root.
My latest attempts at dealing with this are:
1) vitamin D - see my post here under Vitamin D
2) aloe vera gel - 99% certified organic w/some added vitamins a, c, e & herbs (it comes that way, I don't have a recipe). No new hair growth yet but it's only been a week. I get a better thickening effect than I did with castor/coconut oil. I apply it on scalp when hair is still quite damp after shampoo, and of course it gets on the hair shafts too. Leave it in. VERY pleased. Makes it easier to hid the bald patches. Would recommend it to anyone with thin hair as a styling gel.
I have to assume that with both options the thickening effect is temporary (because it's coated). But maybe with time??
P.S. Jenn -- I take black seed oil (nigella sativa) internally. 1 tsp along with 1 tsp honey twice/day -- morning & evening. Have been doing that for about a year. Maybe I'll try some on my scalp.
Best of luck to all...