Additional vegetation, one might think, makes cities more sustainable, because life on earth would be impossible without vegetation. But urban vegetation is often counter-sustainable. Non-renewable energy is used to cut grass, to remove leaves, to supply irrigation water, to quarry peat from natural habitats, to manufacture and dispense fertilisers, herbicides and insecticides. All these activities are carried out on useless patches of so-called "landscaping" which lower urban densities and increase commuter journeys. Well-intentioned but misguided planners have tried to improve city plans by decorating them with liberal quantities of green sauce representing strips of "parkland".