SF has an almost ideal growing environment for plants, but much of the city is hardscape. Greenery helps reduce pollution, stormwater run-off (which could save the city money on water treatment) and local native plants provide habitat for local creatures. Greenery also softens urban space, beautifying the city and helping residents relax. Unfortunately programs such as sidewalk greening and parklets are expensive and grant programs few. How can we enable residents, especially renters, to green their bit of urban space?