International Sunflower Guerrilla Gardening Day is observed worldwide every May 1. This event was initiated by a group of guerrilla gardeners from Brussels in 2007 and promotes the practice of guerrilla gardening, which involves gardening on land that gardeners do not have legal rights to use. Participants are encouraged to plant sunflowers in their neighborhoods, while those in colder regions may opt for other seasonal plants. The guerrilla gardening movement began in the United States during the 1970s and has since spread globally, with various groups and associations active in many countries across Europe, Asia, and America. On this day, GuerrillaGardening.org distributes free sunflower seeds to participants who request them in advance. The event aims to enhance neglected or abandoned spaces, making them more aesthetically pleasing and usable.