As garlic becomes older, however, that germ turns green, grows, and, as many will say, becomes bitter. The Joy of Cooking asserts that garlic with a green germ is old and shouldn't be used.

I f you've ever had a head of garlic sit out too long, you may have noticed small, green shoots coming out of the cloves.

The green sprout is a sign that garlic is losing both its flavor and nutritional value, Xu says. To prevent the green growth, ...