They’re illegal, carry out their deeds at night to avoid detection and are active in a growing number of cities around the world. They’re Guerrilla Gardeners. Their crime? Attacking ugly patches of public land with hand-trowels and flowering annuals in covert greening campaigns. Typical targets include roundabouts, verges and other neglected areas, which are beautified with plants. Richard Reynolds’ website has a global noticeboard of activities plus a how-to guide for beginners.