When the tops (leaves)dry up and fall over. The Southern Exposure Seed Exchange has some good information on growing multiplier onions and garlic in the North and South here.
Welcome! I’m Margaret Roach, a leading garden writer for 25 years—at ‘Martha Stewart Living,’ ‘Newsday,’ and in three books. I host a public-radio podcast; I also lecture, plus hold tours at my 2.3-acre Hudson Valley (NY) Zone 5B garden, and always say no to chemicals and yes to great plants.