In Coorg, leaves of this plant are said to hold maximal medicinal properties on the eighteenth day of the Kakkada month of the Kodava calender (may be in July or August). This is the festival called Kakkada Padinett. On this day, madd toppu leaves are said to emit a strange sweet unique fragrance which is not evident a day prior or after that. They are plucked and made into cakes or sweet porridge. You can read more about it here.
Coorg or Kodava cuisine has some wonderful and distinctive preparations. Do try to sample them when you visit Coorg.