I'm not sure if it is necessary to use both Hibiscus and rosehips. I think one or the other should do it. Rosehips would be used for faded red hair. Not sure about Hibiscus, but it will give warm red hues.
My hair is naturally blonde, but I use Henna on it and it turns it the nicest red! It's not brassy, just a light auburn red. You can control the depth of red with henna.
Whichever one you use, the process takes a while. Better than using chemicals.