European Day of Parks
European Day of Parks is held on May 24. Europarc Federation. This event in the third decade of the month may is annual.
World Endangered Species Day on May 21 (This environmental date is celebrated on the third Friday of May);
Bike-to-Work Day in United States on May 21 (is celebrated on the third Friday of May);
Venezuela Arbor Day on May 30 (celebrated on the last Sunday in May);
Steppe Day in Ukraine on May 30 (2017);
National Tree Day in Benin on June 1 (or Festival of Trees)