Tulsi or the sacred Basil plant is well known for its medicinal properties and is found in front of many Hindu homes. But why is Tulsi plant found in front of all Hindu homes? It is because Lord Vishnu had stated no puja will be complete without offering of Tulsi leaves to Him.
Demon Jalandhar (also known as Shanka Chuda) was so powerful that he drove out the Devas from heaven and established his rule. Devas could not defeat Jalandhar because no weapon could harm him. The demon was powerful because his chaste wife, Vrinda. The pious lady thought of no other men and her prayers and spirituality made her husband invincible.
Vrinda was pious but her husband was using her piety to spread Adharma on earth. To restore Dharma, Vishnu agreed to help the Devas.
Vrinda had always prayed to Vishnu that she should have darshan of Him. Vishnu appeared before in the form of her husband. She served him without realizing that it was Vishnu and not her husband.
Having served another man, Vrinda was no longer chaste and this made Demon Jalandhar vulnerable to weapons and he was overpowered and killed by Devas.
The demons now accused Vrinda of being unfaithful. Vrinda told the world that she had served no one other than her husband. But no one believed her. She then went to Vaikunta to Vishnu to ask him to be her witness.
But she was stopped by Goddess Lakshmi, who was jealous of her as she had served Vishnu. Goddess Lakshmi accused her of being unfaithful by serving Vishnu.
Vrinda then realized that the man whom she had served before her husband died was Vishnu. In a fit of anger, she cursed Vishnu to be born as a Shaligram stone. She also transformed into a Tulsi plant and refused to move from the courtyard of Vaikunta.
Vishnu who knew Tulsi was innocent and faithful, declared that no worship of Him will be complete without offering Tulsi leaves.
From that day Hindu homes started having a Tulsi plant in the courtyard.