TL;DR: There is no single mandatory day for every household: the main Vu Lan ceremony falls on the 15th day of the seventh lunar month, while the cúng chúng sinh custom is usually performed from the 10th up to before the hour of Ngọ on the 15th, and many families choose the late afternoon of the 14th. Choosing either the 14th or the 15th is acceptable as long as the order is kept: offerings to the Buddha, then to the deities, then to the ancestors, and only then to the cô hồn.
Why are there two ways of choosing the 14th and the 15th of the seventh lunar month?
Within the same Rằm of the seventh month festival there are several different rites, each with its own conventional timing. In Buddhism, the main Vu Lan ceremony is on the 15th day of the seventh lunar month[1]. But the cúng chúng sinh custom, that is, the cô hồn offering, is performed earlier by many families, from the 10th up to before noon on the Rằm, and often in the late afternoon or evening[1]. It is this broad window that leads each household to choose a different day, some preferring the 14th for convenience, others waiting until the actual Rằm.
A clear distinction is needed: offerings to the Buddha, the deities and the ancestors are the main part of the ceremony; the cô hồn offering is the almsgiving part and always comes last in the sequence[1]. Old books recorded the rites of the fifteenth day of the seventh month long ago. Kinh Sở tuế thời ký (6th century) writes "七月十五日，僧尼道俗，悉營盆供": on the fifteenth day of the seventh month, monks, nuns and lay people all prepare bowl offerings. Phan Kế Bính's Việt Nam phong tục (1915) cites the Song-dynasty Mộng hoa lục: at Trung nguyên, people used a three-legged bamboo stand called vu lan, hung money and paper goods on it and burned them.
What time is reasonable for the cô hồn offering?
According to common custom, cúng chúng sinh should be performed in the late afternoon or evening, when the sun has faded, because folk belief holds that only then can the spirits receive the offerings[1]. There is no fixed clock time; the offering is usually set out before full darkness.
This is a convention of folk belief, not a law or a mandatory doctrine. People avoid making the cô hồn offering at midday, the hour of Ngọ (11 a.m. to 1 p.m.), because they believe the yang energy is strong and the spirits dare not come to receive it. Some households make the offering early in the morning if they are busy, as long as they do not forget that the cúng chúng sinh must come after the ancestor offering on the same day.
What rites make up the Rằm of the seventh month sequence?
According to common guidance, the Rằm of the seventh month ceremony in each household is usually performed in the order: offerings to the Buddha, to the deities, to the ancestors, and finally to the chúng sinh[1]. Each rite has its own meaning and offerings:
| Rite | Usual timing | Main offerings | Meaning |
|---|---|---|---|
| Offering to the Buddha | First in the sequence | Vegetarian rice, five fruits | To seek merit and clear karma for deceased ancestors[1] |
| Offering to the deities | Before the ancestor offering | Sticky rice, boiled chicken, bánh chưng, tea, wine, fruit, fresh flowers | To ask the deities to protect the family's health and peace[1] |
| Offering to the ancestors | After the offering to the deities | Vegetarian or non-vegetarian rice, votive paper money | To show respect and wish the ancestors a full life[1] |
| Offering to the chúng sinh (cô hồn) | From the 10th to before noon of the Rằm, usually late afternoon | Porridge, rice, salt, sweets, fruit | Almsgiving to homeless spirits[1] |
The cúng chúng sinh tray is set out separately, in the yard or outside the front door[3], not on the ancestor altar.
Why do Vietnamese people make the cô hồn offering on the Rằm of the seventh month?
The cô hồn custom stems from the belief in spirits who died without anyone to worship them. According to Nguyễn Văn Huyên (as quoted by Nguyễn Thị Vân), Vietnamese folk belief holds that hồn and vía reside in the human body, and at death the hồn leaves the body; besides each family's own ancestral hồn there are countless ghosts influencing life, including the hồn of unfortunate people who died without descendants, drowned in rivers, ponds or the sea, wandering miserably with no place to dwell[2]. Such spirits are collectively called cô hồn.
The Rằm of the seventh month is regarded as the occasion of "xá tội vong nhân", when the spirits in the underworld have the gates of hell opened to come up to the world and receive offerings[3]. Therefore people make the almsgiving ceremony so that the spirits do not cause trouble, and at the same time pray for the family's peace.
Is the 14th or the 15th the correct day?
No doctrinal text requires choosing the 14th or the 15th. What the customary sources agree on is the time frame: cúng chúng sinh is performed from the 10th to before noon of the Rằm, while the main Vu Lan ceremony is on the 15th[1]. Thus both the 14th and the 15th fall within the valid window. Which day to choose depends on the family's circumstances, work, and local habit.
Gregorian dates, weekdays and day stems-branches of the 14th and the Rằm of the seventh lunar month for the next five years, in Vietnam time:
| Lunar year | 14th day of the 7th lunar month | 15th day of the 7th lunar month (Rằm) |
|---|---|---|
| 2027 Đinh Mùi | Sunday 15 August 2027, a Bính Dần day | Monday 16 August 2027, an Đinh Mão day |
| 2028 Mậu Thân | Saturday 2 September 2028, a Canh Dần day | Sunday 3 September 2028, a Tân Mão day |
| 2029 Kỷ Dậu | Thursday 23 August 2029, an Ất Dậu day | Friday 24 August 2029, a Bính Tuất day |
| 2030 Canh Tuất | Monday 12 August 2030, a Kỷ Mão day | Tuesday 13 August 2030, a Canh Thìn day |
| 2031 Tân Hợi | Sunday 31 August 2031, a Quý Mão day | Monday 1 September 2031, a Giáp Thìn day |
If the 14th is chosen, many households make the offerings to the Buddha, the deities and the ancestors first, then the cô hồn offering in the late afternoon of the same day. If it is left to the 15th, the window for cúng chúng sinh only runs until before noon on the Rằm[1], so the cô hồn offering is usually made early in the day or moved to the late afternoon of the 14th.
Common misunderstandings about the day and hour of the offering
Is it only on the 15th of the seventh month that the rite is efficacious?
No. Customary sources record the cúng chúng sinh as made between the 10th and before noon on the Rằm[1], and the Rằm offerings usually begin from the 10th day of the seventh month[3].
Is it a problem to make the cô hồn offering at noon?
It is a folk avoidance, not a prohibition; busy households may make the offering earlier in the day, as noted above.
Should votive paper be burned when making the cô hồn offering?
This is a point on which the schools do not agree. Many families still burn votive paper because they believe the spirits need offerings in the underworld. The Vietnam Buddhist Sangha has repeatedly advised against burning votive paper during Vu Lan, urging people instead to spend the money on charity, caring for parents and helping those in need[4]. This is the guidance of a religious organization, not a legal regulation.
Nhật Nguyệt's suggestion
If a family wants to keep the traditional custom without fuss, they can choose the following: make the offerings to the Buddha, the deities and the ancestors on the 14th or the morning of the 15th, make the cô hồn offering in the late afternoon of the 14th (or the morning of the 15th if busy), place the cô hồn tray in the yard or before the door, with simple offerings of porridge, rice, salt, and sweets. More important than anything is that this occasion is for remembering ancestors and visiting living parents, not for chasing a fixed day and hour.
