The term “guerrilla” may bring to mind a small band of armed soldiers, moving in the dead of night on a stealth mission. In the case of guerrilla gardening, the soldiers are planters, the weapons are shovels, and the mission is to transform an abandoned lot into a thing of beauty. Once an environmentalist’s nonviolent direct action for inner-city renewal, this movement is spreading to all types of people in cities around the world.These modern-day Johnny Appleseeds perform random acts of gardening, often without permission. Typical targets are vacant lots, railway land, underused public squares, and back alleys. The concept is simple, whimsical, and has the cheeky appeal of being a not-quite-legal call to action. Dig in some soil, plant a few seeds, or mend a sagging fence—one good deed inspiring another, with win-win benefits all around. Guerrilla Gardening outlines the power-to-the-people campaign for greening our cities. Tips for effective involvement include:• Finding plants and seeds cheap (or free) • Handling city officials • Getting the dirt on soil • Planting to bring back the birds • Knowing when to ask firstSocial activists, city dwellers, and longtime gardeners will delight in this fast-paced and funny call to arms. David Tracey is a journalist and environmental designer who operates EcoUrbanist in Vancouver. He is executive director of Tree City Canada, a nonprofit ecological engagement group.