Cooks classify this good-for-you green three ways: Curly-leaf spinach has crinkled leaves; flat-leaf spinach, often sold frozen or canned, has smoother leaves and a slightly milder flavor; and baby spinach is simply the flat-leaf type harvested when very young and tender. Spinach is low in calories but high in vitamins C and A. It’s also rich in folate and riboflavin.
Both curly- and flat-leaf spinach are sold in bunches and bags, and baby spinach comes prepackaged or loose. Refrigerate spinach in a plastic bag; it spoils quickly, so use it within a couple of days.
Baby spinach doesn’t need to be trimmed, but you’ll want to cut off the tough root ends of curly- and flat-leaf spinach. Always wash spinach, even when it’s labeled “prewashed”: Submerge it in a bowl of cool water to dislodge any grit, then spin dry.
Baby spinach is wonderful lightly steamed or used raw in salads. Mature curly- or flat-leaf spinach has thick stems and leaves and a stronger spinach flavor, so it’s best when cooked. Sauté it with garlic in olive oil, add it to a stir-fry, toss it into a soup or cook it in a little water until it wilts, then stir into a warm pasta dish.