Vegetation in the video game Once Human plays a major role in both the atmosphere and survival experience of the post-Starfall world. The landscape is covered in dense forests, overgrown grasslands, wild shrubs, towering trees, and mutated plant life that has been altered by the spread of Stardust. Nature has reclaimed much of civilization, with abandoned towns, roads, and industrial sites often buried beneath thick layers of vegetation.

Players can harvest a wide variety of plants, herbs, flowers, mushrooms, and crops for crafting, cooking, medicine, and farming. Some regions feature unique flora adapted to their environments, from lush temperate forests to frozen wildernesses and contaminated zones. Certain plants also exhibit unusual behaviors or appearances due to Stardust exposure, adding to the world's mysterious and dangerous atmosphere.

The rich vegetation system not only enhances immersion through realistic ecosystems and environmental storytelling but also provides essential resources that support exploration, base building, farming, and long-term survival throughout the world of Once Human.