By Mengyuan Dong

San Franciscans have long put their food waste in the City’s green bins for composting, but Chris Krupa says there is a better way to compost. Krupa, a project manager for garden school Garden for the Environment, led a workshop on Sept. 11 to show Sunset residents how to turn eggshells and coffee grounds into nutrient-rich mixtures for their gardens. 

“People coming here are already into the environment,” said Krupa. “We just empower them.”

The workshop, which took place at Garden for the Environment on Seventh Avenue at Lawton Street, gave participants hands-on instructions for making compost at home. Krupa said composting gives the growing number of home gardeners fertilizer for cultivating plants and vegetables and saves food waste from landfills. Some gardeners said they appreciated getting the composting tips for taking the mystery out of the process. 

Workshop participant Linda Wu said she started coming to Garden for the Environment to be outdoors during the pandemic. She is not alone. According to plant wholesaler Bonnie Plants, more than 20 million first-time U.S. gardeners picked up the hobby in 2020.

Wu said she found composting overwhelming at first. 

“Just coming here and you see, oh, everybody is figuring it out as they go,” she said. 

The workshop introduced participants to the traditional three-bin composting system, which involves creating three different compost piles, each one in a different stage of completion. Wu and the others chopped up raw materials, including dried leaves and branches, mixed them with coffee grounds, manure and water into the appropriate pile, and sifted finished compost out of the last pile.

The worm bin, another compost system, takes less maintenance and less space. A 20-by-20-inch bin full of soaked newspapers, kitchen scraps and shredded scrap paper can house more than 300 worms, which decompose the material into a dark, soft compost that feels like sponge cake. 

Kim Garcia-Meza, who led the workshop with Krupa, said composting has broad environmental benefits. Every day, food waste ends up in landfill bins, even in households with a green bin to fill. And food that ends up in landfills creates methane, a greenhouse gas more potent than carbon dioxide. 

Food waste also decomposes far more slowly in a landfill. 

Without oxygen, it could take up to 25 years for a head of lettuce to decompose in a capped landfill, Krupa said. “But in a compost system, it could be like a week.”

For more information, go to https://www.gardenfortheenvironment.org