To make yellow colour at home, blend turmeric powder with gram flour in equal proportions until thoroughly combined. 
 

To make green colour, grind dry neem leaves into a powder. Alternatively, boil spinach leaves in water, grind them into a paste, allow it to dry and use it as green Holi colour. 
 

For a vibrant red colour, grind dried red hibiscus flowers or dried rose petals into a powder. You can also make the red colour using dried pomegranate peel powder. 
 

For orange colour, add a pinch of turmeric powder to red sandalwood powder. You can also make the orange colour by drying Palash flowers and grinding them into a powder. 
 

To make blue colour, use flowers of Aparajita plant (Butterfly Pea). Firstly, wash them thoroughly and dry the flowers. Then grind them into a fine powder.