Samjinnal is one of sesi pungsok or Korean traditional customs by season, which falls on the third day of the third month in the Chinese calendar. It was called samjil (삼질) in old Korean language and referred to as sangsa, wonsa (원사, 元巳), sungsam (중삼, 重三), sangje (상제, 上除) or dapcheongjeol (답청절, 踏靑節) in hanja. Samjinnal implies the overlapping of Sam (three). According to Choi Namseon, samjil was derived from the consonants of Samil, and Sangsa is defined as the first snake day of the 3rd lunar month
During Samjinnal, people pick out azalea flowers and knead it with glutinous rice dough to make Hwajeon, a Korean traditional rice cake. Mung bean powder is used to make mung bean noodles, and is also occasionally used with the azalea flowers. By dyeing the mung bean powder with red water, a seasonal dish called Sumyeon can be prepared. Other than this, white bubble rice cakes made with red bean paste called Santteok, Goritteok made from glutinous rice, pine endodermis and mugwort, and Ssuktteok made from glutinous rice and mugwort leaves are eaten this day.