From the day of Atham to Uthradam, floral carpets named Pookkalams will start adorning homes across Kerala. On the day of Thiruvonam, Thrikkakara Appan is placed on these pookkalams and worshipped. Placed on the top of a ‘Peetham’ on a plantain leaf and a ‘kalam’ that is drawn using rice batter, Thrikkakara Appan is worshipped. It is also referred to as ‘Mathevar’. Maveli, Thrikkakara Appan and Sivan are the three forms of Mathevars. There are disagreements on whether Thrikkakara Appan is Maveli or Vamana. However as per the concepts of Thrikkakara temple, Mathevar is none other than lord Vishnu.
Mahodayapuram Perumal of Thrikkakara used to celebrate Onam from the Thiruvonam day in Karkkidakam to the Thiruvonam day in Chingam. It is believed that 56 rulers of princely states, samanthas and various landlords used to be a part of this celebration. When this tradition was not followed once, the perumal ordered that those who couldn’t reach Thrikkakara should celebrate Onam in their households. Legend goes that it is after this incident that Thrikkakara Appans began to be kept and worshipped in homes during Onam days. This is done in different ways in different regions. In some places Thrikkakara Appan is placed from Uthradam and Mahabali is placed on Thiruvonam. With Mahabali, various other forms including Muthassi Amma, Kutti Pattar, Ammi, Aattukallu, Arakallu and Ural are also kept. In Valluvanad, there are people who keep Mathevar from the day of Atham. In Malabar, Mathevar is also kept in the front of homes. Songs are sung to make the occasion celebratory.
Poomoodal, a religious ritual, is held in certain parts and ‘Ada’ is cooked as an offering to Thrikkakara Appan on Thiruvonam. In central Kerala, there is also a ritual of shooting an arrow through the ada using a bow. The rice batter ‘kolam’ is drawn in various parts of homes by certain people. Even though there are differences in the way it is performed, the ritual of placing Thrikkakara Appan and subsequent worships are common throughout Kerala. In general, this is practised till the 5th day of Onam.