The spring season, during which the weather changes, is believed to cause viral fever and cold. The playful throwing of natural coloured powders, called gulal has a medicinal significance: the colours are traditionally made of neem, kumkum, haldi, bilva, and other medicinal herbs suggested by ??yurvedic doctors.
Many colours are obtained by mixing primary colours. Artisans produce and sell many of the colours from natural sources in dry powder form, in weeks and months preceding Holi. Some of the traditional natural plant-based sources of colours are: