Ching Ming -> Grave-Sweeping Day, observed on April 5 Lunar Calendar. According to my research, this ancestor worshipping day originated from China where family members gathered together to weed and clean the headstone, replace the wilted flowers with fresh ones and also offer incense, paper money and food to their ancestor as a virtue of filial piety.

Ching Ming is a major public festival in Singapore… as you can see… people already startws their Ching Ming visiting as early as 3 weeks before the actual day…
Along Lim Chu Kang Road…

Ching Ming is also indicated on traditional Japanese calendars, where their culture has a similar observance. In Korean culture, the observance is known as Hansik.