Jason Mraz helped out community gardeners and school kids at La Casita Verde Garden in Williamsburg Wednesday.

Mraz and volunteers planted cover crops and built new furniture like compost benches as part of NYC Parks' Green Thumb event.

Mraz says more gardens are needed in Brooklyn. "Brooklyn's got great spots where its potential could really be used to combat climate change, to help feed the community, or to just give someone a sense of peace," he said.

Mraz kicks off his five-borough tour Wednesday in Brooklyn.