Qingming is an opportunity to remember and honor ancestors at grave sites. Young and old pray before the ancestors, sweep the tombs and offer food, tea, wine, chopsticks, joss paper, and/or libations to the ancestors. The rites have a long tradition in Asia, especially among farmers. Some people carry willow branches with them on Qingming or put willow branches on their gates and/or front doors. They believe that willow branches help ward off the evil spirit that wanders on Qingming.
On Qingming, people go on family outings, start the spring plowing, sing, and dance. Qingming is also a time when young couples traditionally start courting. Another popular thing to do is to fly kites in the shapes of animals or characters from Chinese Opera.
Tomb-Sweeping Day is a traditional Chinese festival on the first day of the fifth solar term of the traditional Chinese lunisolar calendar. This makes it the 15th day after the Spring Equinox, either 4 or 5 April in a given year
The present importance of the holiday is credited to the Emperor Xuanzong. Wealthy citizens in China were reportedly holding too many extravagant and ostentatiously expensive ceremonies in honor of their ancestors. In ad 732, Emperor Xuanzong sought to curb this practice by declaring that such respects could be formally paid only once a year, on Qingming.
The Qingming festival holiday has a significance in the Chinese tea culture since this specific day divides the fresh green teas by their picking dates. Green teas made from leaves picked before this date are given the prestigious ‘pre-qingming’ 清明前 designation which commands a much higher price tag. These teas are prized for having much lighter and more subtle aromas than those picked after the festival.
Source: wiki https://en.wikipedia.org/wiki/Qingming_Festival