
When we were very young, every sunday used to be the day for traditional oil bath, which included, an oil massage with Til oil, followed by being bathed with shikhakai and powder made of dry flowers and herbs (called vasanai podi). My mother never used soap after this bath coz, she always maintained that mild fragrance of shikhakai and kastoori manjal was more than enough.
But once in a while, my mother also used the following mixture as a natural conditioner for the hair.
1. Soak some leaves (5-6) of the hibiscus plant in a cup of curd for half hour.
2. Grind it into a fine mixture like a cream
3. Apply it on the scalp and hair generously and leave it on for say a hour.
Wash it off with water and follow it with shampoo if you desire, though if you can avoid it, nothing like it.

This leaves your hair soft and conditioned naturally.