Pitru Paksha falls in the month of Bhadrapada and starts from Purnima and extends until Amavasya. This particular period is regarded as very auspicious as it is stated in the Hindu scriptures that our ancestors visit earth to accept the offerings made by their family members. In fact, it is also said that ancestors survive on the shradh and Tarpan that is offered in the Pitru Paksha. Therefore, one must not ignore performing these rituals. You can get immense benefits by performing shradh ceremonies during Pitru Paksha also called as the Mahalaya Paksha than what you get by performing the annual shradh ceremonies.
Trayodashi Shradh
Most of the times, Dwadashi and Trayodashi tithis fall on the same day thus shradhas are performed on the same day. Trayodashi shradh is performed of the family members who passed away on the Trayodashi tithi. In addition, shradh of children who died in their young age is also done on this day irrespective of the month, paksha and tithi in which they died.
This year, the Magha nakshatra comes on the Trayodashi and therefore this shradh is also called as Magha shradh. Pitrus rule this Magha nakshatra and therefore it is very special to execute the shradh ceremonies when this nakshatra exists during the Pitru Paksha. This year, Trayodashi shradh falls on 26th September 2019.
Why is Pitru Paksha regarded as auspicious to perform shradh and Tarpan?
Hinduism believes in life after death and so regards this Pitru Paksha highly favorable time to remember the great deeds of our ancestors. By performing Shradh puja and offering Tarpan, descendants appease their ancestors and are thus get blessed by them.