A festive reforestation activity where citizens of Puerto Princesa City and people from all walks of life flock to celebrate a Feast of the Forest, by planting thousands of different tree species in the city's denuded forest zones. Related activities are eco-camping, games and contests, and performances by environmental artists. Celebrated annually at the onset of the rainy season, it is the people's collective performance of its environmental duties of giving back something to Mother Earth.

Barangay Irawan's Irawan Watershed is a primary water source of Puerto Princesa residents. The watershed has been devastated by rampant slash-and-burn farming  and illegal logging  during the 1980’s. The tree-planting festival is geared to maintain the water table and restore wildlife habitat in the watershed. The planting activity already achieved the 100 hectare target to rehabilitate the watershed.