Budhavara Vrata (बुधवार व्रत) is the Wednesday vrata of Budha, the son of Soma, for removing the ill effects of Budha. The Vratraj gives it, as its editor added it, from the Jayasimha Kalpadruma: it is begun on a Wednesday with Vishakha nakshatra and kept for seven naktas.
How to keep the vrata
Place a gold image of Budha in a bronze vessel, cover it with two white cloths, and offer a white garland and white unguent.
Give rice cooked with jaggery (guda-odana) to a Brahmana, praying: बुध त्वं बोधजनको बोधदः सर्वदा नृणाम्।
Offer homa with ghee and sesame with Budha's mantra, 108 or 28 samidhs dipped in honey, ghee and curd.
When to eat
Nakta: one meal at night, on each of the seven days. The meal is taken in Pradosha; each day's Pradosha time is shown with the dates above.
विशाखासु बुधं गृह्य सप्त नक्तान्यथाचरेत्।
viśākhāsu budhaṃ gṛhya sapta naktāny athācaret.
"Taking up (the vrata of) Budha on Vishakha, keep seven naktas."
Jayasimha Kalpadruma, Budha Vrata (Vratraj, editor's addition)