The floral carpet, known as ‘Onapookkalam’, is made out of the gathered blossoms with several varieties of flowers of differing tints pinched up into little pieces to serve the decorator's purpose. It is considered a work of art accomplished with a delicate touch and a highly artistic sense of tone and blending. When completed, a miniature pandal (umbrella) hung with little festoons is erected over it. The pookkalam is similar to Rangoli which is made of powders of various colors and is popular in North India.
Traditionally, Atthapookalams (pookalam made on the Atham day) included flowers endemic to Kerala and the Dashapushpam (10-flowers), but nowadays all varieties of flowers are used.Earthen mounds, which look somewhat like square pyramids, representing Mahabali and Vamana are placed in the dung-plastered courtyards in front of the house along with the Pookalam, and beautifully decorated with flowers. In the recent years, the floral designs have evolved from the traditional circular shape to unique designs depicting different cultural and social aspects of Kerala life. All over Kerala, Pookalam competitions are a common sight on Onam day.People start putting atha-pookalams from Atham ( First day of 10-day festival ) till thiruvonam, while only some put Onam Pookalams till the 28th day after thiruvonam.