Datura in Shiv Puja helps in giving up the bitterness and poison of your mind.
The adornment of Lord Shiva is very mysterious and different. It includes snakes, ash, poisonous & wildflowers, and leaves. Such adornment tells that Lord Shiva accepts all of them too which people have kept away from themselves. That is, even those things which are of no use, Lord Shiva wears it on himself.
Shiva adopts what people give up
Lord Shiva accepts Datura (A type of plant) and Bel leaves as adornment. This generous form of Shiva indicates that Shiva accepts what society despises. The idea behind offering poisonous fruits like datura in Shiva worship is to avoid bad behaviour and bitter words in personal, family and social life. Do not have a sense of selfishness, keep a sense of the interest of others. Only then can the life of others be happy with you.
Renunciation of Bitterness
The message that Lord Shiva gives by loving Datura is that by when one goes to the temple and offers datura to Shivling, one should take a pledge to remove the bitterness of the mind and thoughts and adopt the sweetness. To do so would be true worship for the happiness of Lord Shiva.
According to Devi Bhagavata Purana
From the religious point of view, the reason for this is mentioned in the Devi Bhagavata Purana. According to this pious book, when Shiva drank the poison that came out of the churning of the ocean, he started getting distraught. Then Ashwini Kumars removed the distraction of Shiva with medicines like bhang, datura, bel. Since that time Shiva is fond of bhang and datura. Whoever offers Bhang and Dhatura to Lord Shiva, Shiva is pleased with him.
Founder, Upgrading India