In Hinduism, Havan (also known as Homa) is a sacred ritual in which offerings are made into a consecrated fire 
while chanting Vedic mantras. The fire (Agni) is regarded as a divine witness and a carrier of prayers to the gods. The ash that remains after the Havan is considered extremely holy, as it is imbued with the spiritual energy of the mantras and the presence of Agni Dev.
Throwing away or disrespecting this ash is considered inauspicious. According to scriptures and astrology, when used correctly, Havan ash enhances positive energy in the home, protects against negative influences, and supports health and prosperity. Here are five important ways to use Havan ash properly:
1. Apply as a Tilak on the Forehead
The first and most important use of Havan ash is applying it as a tilak on the forehead. This helps calm the mind, ward off the evil eye, and increase positive energy.
Men may apply three horizontal lines, while women may apply it in the form of a bindi. Regular application of Havan ash as a tilak boosts self-confidence and protects against negative energies.
2. Sprinkle at the Main Entrance of the House
A small amount of Havan ash can be sprinkled at the main entrance of the house, or tied in a red cloth and hung near the doorway. This practice helps prevent negative energy, evil eye, and hostile influences from entering the home.
According to Vastu Shastra, this is considered highly auspicious. If there are frequent conflicts or financial difficulties at home, mixing the ash with water and sprinkling it at the entrance is believed to bring peace, harmony, and prosperity.
3. Offer It to Tulsi or Peepal Tree
Placing Havan ash at the roots of a Tulsi plant or a Peepal tree is considered highly meritorious. Tulsi is regarded as dear to Lord Vishnu, and the Peepal tree is believed to be the abode of all deities.
This practice helps keep the plant healthy and increases positive vibrations in the home. It is also beneficial for the environment. If Tulsi is not available at home, the ash may be offered to Tulsi plants in a temple. This is believed to multiply the spiritual merit of the Havan and bless the family with health and prosperity.
4. Mix with Bath Water
A small quantity of Havan ash may be mixed into bath water for purification of the body and mind. This is believed to help relieve skin problems, allergies, and negative energies.
Women may take such a bath after menstruation, and men may do so after an inauspicious event. Pouring this water over the head is said to reduce mental stress and encourage positive thinking. This remedy is especially considered beneficial during illness or emotional unrest.
5. Use in Garden or Farmland
If there is a garden or potted plants at home, Havan ash can be mixed into the soil. It acts as a natural fertilizer and promotes healthy plant growth.
When added to farmland, it is believed to improve crop quality and increase prosperity. Scriptures mention that Havan ash purifies the soil and helps keep harmful insects away.
By following these practices, one can receive the complete spiritual benefits of Havan and maintain a positive atmosphere at home. Havan ash should never be thrown into flowing water or discarded as waste, as doing so is considered disrespectful and inauspicious.