The nonprofit behind the Union Square Greenmarket plans to open a new community space in the neighborhood to host events and classes on sustainability and nutrition, and provide a spot for other nonprofits in the city to gather near Union Square, according to GrowNYC Assistant Director Julie Walsh. The space, called “Project Farmhouse,” is expected to open at 76 E. 13th St., near Fourth Avenue, by November with a test kitchen, a conference room and a vertical grow wall with moving trays designed to rotate plants so they all get the ideal amount of water, fertilizer and light, said Kate Chura of GrowNYC, who is overseeing the project.