TL;DR: Mang Chủng (芒種) is the 9th of the 24 solar terms, usually beginning around June 5 or 6 in the Gregorian calendar, when Tiểu Mãn ends, and lasting until Hạ Chí begins, usually on June 21. It is the term that opens the Ngọ month. According to Tam thống lịch, the name means that awned grain (mang) can now be sown (chủng). In old Eastern calendrical science, it is a key marker for placing the intercalary term in the Kỳ Môn Độn Giáp system, and folk tradition links it to farming work, disease prevention, and light, cooling food.
What is Mang Chủng and when does it fall?
Mang Chủng is the 9th of the 24 solar terms of the year, usually beginning around 5 or 6 June in the Gregorian calendar, when Tiểu Mãn solar term has just ended, and ending when Hạ Chí solar term begins[1]. Hạ Chí usually starts on 21 June, in some years on the 20th or 22nd. In the common way of reckoning, the 24 solar terms are 24 periods, each lasting 15 or 16 days, describing 24 different weather phases of the year[1].
Mang Chủng begins when the Sun reaches 75 degrees of ecliptic longitude. It is the term that opens the Ngọ month, the 5th month counted by solar terms; Hạ Chí is the middle term of that month. In Bát Tự, a person born after the start of Mang Chủng is counted in the Ngọ month, while the start of Hạ Chí does not change the month.
Start times of Mang Chủng in recent years:
| Year | Gregorian date | Start time (Vietnam time) |
|---|---|---|
| 2025 | 5 June | 16:50 |
| 2026 | 5 June | 22:37 |
| 2027 | 6 June | 04:23 |
| 2028 | 5 June | 10:09 |
| 2029 | 5 June | 15:57 |
| 2030 | 5 June | 21:45 |
The name "Mang Chủng" is written in Han characters as 芒種. In the ancient solar term system, terms were usually named after natural phenomena or the farming work under way. "Mang" (芒) refers to the pointed awn on a rice ear, while "chủng" (種) means sowing seed. The common folk understanding is that this is the time when the awned rice has ripened and must be harvested, and at the same time when seed must be sown for the next crop. The book Tuế thời quảng ký by Trần Nguyên Tịnh of the Southern Song dynasty, in its section on the middle month of summer, quotes Tam thống lịch: "芒種為五月節夏至為五月中氣芒種者言有芒之穀可稼種也"[2], meaning that Mang Chủng is the term of the 5th month, Hạ Chí is the middle term of the 5th month, and the name Mang Chủng comes from awned grain now being ready to sow.
Why do solar terms have different starting dates each year?
Solar terms are divided by the position of the Sun on the ecliptic, each term corresponding to 15 degrees of ecliptic longitude. A tropical year lasts about 365.24 days, so each year the start time moves later by nearly 6 hours; the extra 29 February of a Gregorian leap year pulls it back earlier. In the table above, Mang Chủng 2026 starts at 22:37 on 5 June, moves to 04:23 on 6 June in 2027, then returns to 10:09 on 5 June in the leap year 2028.
What does Mang Chủng mean in ancient calendrical science?
In ancient Eastern calendrical science, Mang Chủng is not only a weather marker but also a reference point for setting the intercalary term in the Kỳ Môn Độn Giáp system. The book Độn giáp diễn nghĩa states clearly that the rule for setting the intercalary term must be based on the two terms Mang Chủng and Đại Tuyết[3].
In its section on the rules of advancing spirit, connecting qi and setting the intercalation (Siêu thần tiếp khí trí nhuận quyết), the book writes: "置閏定在芒種大雪之後設遇小滿小雪二氣之交雖超九日十日不可置閏"[3], meaning the intercalation is set only after Mang Chủng and Đại Tuyết; at the change of Tiểu Mãn or Tiểu Tuyết it is not set even if the lead reaches nine or ten days. The reason the book gives is that the Kỳ Môn layouts take the two solstices as the points where yang peaks and yin ends: "葢竒以冬夏二至陽極隂終"[3]. The verse in the same section ends with: "要知置閏在何時端在芒種與大雪"[3], that is, to know when to set the intercalation, look to Mang Chủng and Đại Tuyết.
Another interpretation in the book Thuật số Lạc Thư holds that, since the starting point of the Earth is Đông Chí solar term, the intercalary term after 3 years must be placed before Đông Chí solar term, that is, at Đại Tuyết solar term; while in the case where two and a half years have already been intercalated, the intercalary term must be set at Mang Chủng so that Hạ Chí solar term follows[4]. This is the explanation of one school, not a general convention for all calendrical systems.
Table comparing the position of Mang Chủng across systems
| System | Position of Mang Chủng | Note |
|---|---|---|
| 24 solar terms | 9th term | After Tiểu Mãn, before Hạ Chí[1] |
| Kỳ Môn Độn Giáp | Marker for setting the intercalary term | Together with Đại Tuyết solar term[3] |
| Month pillars | Term that opens the Ngọ month | Hạ Chí is the middle term of this month[2] |
| Thái Âm arriving at the mountain | Thái Âm arrives at the Bính mountain | From the table pairing 24 mountains with 24 solar terms[5] |
What customs does Mang Chủng have in Vietnam?
In the Vietnamese documents that survive, Mang Chủng hardly appears as a separate festival with fixed rituals. This differs from terms such as Thanh Minh, Đoan Ngọ or Trung Thu, which are recorded in many books of customs. The book Đại Nam nhất thống chí, compiled by the Quốc sử quán of the Nguyễn dynasty, in the section on the customs of Hà Tĩnh province, records that the people observed the rituals of Nguyên Đán and Đoan Dương festivals just as in Nghệ An. Mang Chủng is not mentioned as a separate festival in this passage.
The book Gia lễ giản yếu by Dương Bá Trạc (1932) kept only the Nguyên Đán, Thanh Minh and new rice festivals for offerings to ancestors, while it considered festival days such as Đoan Ngũ, Thượng Nguyên, Trung Nguyên and Trung Thu to be meaningless and to be abandoned altogether[6].
Mang Chủng falls in midsummer, with hot, humid weather and much rain. In folk custom, people often remind one another to take care of their health during this period: eat cooling dishes, avoid heavy food, and keep the house airy. This is an oral habit, not a ritual tied to the name of the term.
Why is Mang Chủng tied to farming?
In the same section on the middle month of summer, Tuế thời quảng ký quotes the Chu thư Thời huấn, which divides this term into three pentads of five days each: "芒種之日螳螂生後五日鶪始鳴後五日反舌無聲"[2], that is, on the day of Mang Chủng the mantises hatch, five days later the shrike begins to call, and five more days later the mimic bird falls silent. The book also records a custom of the people of Min (Fujian, China): "芒種後逢壬日為出梅農人以得梅雨乃宜耕稼"[2], meaning the plum rain season ends on the Nhâm day after Mang Chủng, and farmers who get the plum rains can plough and plant well. This is a Chinese custom, not a Vietnamese one.
In Vietnam, the book Nam Kỳ phong tục nhơn vật diễn ca by Nguyễn Liên Phong (1909) depicts the fields of Nam Kỳ at that time, with lines such as "Dân cư rẩy ruộng ê hề lúa khoai" (the villagers' fields and gardens abound in rice and sweet potatoes)[7].
Mang Chủng in feng shui and date selection
The book Sử dụng la bàn has a table of Thái Âm arriving at the mountain, pairing the 24 solar terms with the 24 mountains of the compass, one mountain for each term. According to that table, in Mang Chủng Thái Âm arrives at the Bính mountain[5].
The book Tìm hiểu Cổ dịch Huyền không học also has a table of Thái Dương arriving at the mountain and at the facing direction by the 24 solar terms, which includes Mang Chủng[8].
It should be noted that these are conventions of individual feng shui schools, not scientifically verified knowledge. Different schools may have different ways of placing stars and choosing directions for the same solar term.
Mang Chủng and the choosing of auspicious and inauspicious days
In date-selection almanacs, the twelve day officers (Kiến, Trừ, Mãn, Bình...) are counted from the month branch, and the month branch changes with the solar terms, not with the first day of the lunar month. From the start of Mang Chủng the month branch is Ngọ, so the Ngọ days of that month, from Mang Chủng to Tiểu Thử, carry the Kiến officer.
Common misunderstandings about Mang Chủng
It may be misunderstood that Mang Chủng is a festival with offerings like Tết Đoan Ngọ. In fact Mang Chủng is a solar term, with no ritual of its own in the books of customs cited above. The major festivals are tied to specific lunar dates, while solar terms are tied to the position of the Sun, so they stay almost fixed in the Gregorian calendar and move in the lunar one.
The second misunderstanding is to identify Mang Chủng with Tết Đoan Ngọ. Tết Đoan Ngọ is the 5th day of the 5th lunar month and falls between late May and late June in the Gregorian calendar depending on the year, so in many years it lies within the Mang Chủng period, but the two are not the same marker. In 2026, Đoan Ngọ is on 19 June, while Mang Chủng starts on 5 June.
The third misunderstanding is to think that Mang Chủng is only meaningful for agriculture. In fact, in numerological systems such as Kỳ Môn Độn Giáp, Mang Chủng is also a marker for setting the intercalary term, affecting how the layout is placed throughout the whole system[3][4].
Nhật Nguyệt's suggestion: How should Mang Chủng be used sensibly?
Nhật Nguyệt's suggestion: If you are interested in Mang Chủng because you want to follow the weather or arrange farming work, treat it as an important seasonal transition marker. This is a hot, humid period with much rain in the North, so pay attention to preserving agricultural produce and preventing seasonal diseases. If you are interested in Mang Chủng because of numerological systems, remember that each school has its own conventions, and these conventions have no scientifically verified basis. This article does not offer advice on finance, health or personal destiny based on solar terms.
