Plant a garden. Listen to birdsong. Sit quietly in a park without checking your phone. These activities are examples of ecotherapy, a form of mental health treatment based on the idea that nature has healing powers. “If you hold moist soil for 20 minutes, the soil bacteria begin elevating your mood,” says Craig Chalquist, an innovator in this new field. “You have all the antidepressant you need in the ground.” Chalquist maintains that it helps even more to give something back to nature—not just looking at trees, but caring for them (Atlantic, October).