Observed on the 1st of November each year, All Saints' Day is a Christian holiday which is honoured to celebrate the lives of all saints, whether well-known or obscure.
Originating from Anglican and Roman Catholic tradition, the modern incarnation of All Saints' Day in many countries around the world also involves remembering the lives of deceased relatives and loved ones. This involves practices such as lighting candles and laying flowers on the graves of family members.
Given that All Saints' Day is observed as a celebration of life as opposed o a grieving of passing, it's not uncommon to see colourful flowers such as roses alongside more traditional sympathy flowers such as white lilies. In France and Belgium a popular custom involves leaving chrysanthemums on the tombs of the beloved.
All Saints' Day is often associated with All Souls' Day, which takes on the 2nd or 3rd of November, and it's not uncommon for religious observances to tie together within the greater season of Allhallowtide. Whilst not so widely observed in the UK, All Saints' Day is still quite common around Europe and the Americas. That said, it's not unheard of in the UK to lay flowers at cemetries around the Allhallowtide season.