Season: Spinach is available year round in supermarkets, though best during winter and spring months.
Varieties: There are two main varieties: curly (savoy spinach) and flat-leaf. Flat-leaf spinach can be broad and round, or pointed; the young leaves (baby spinach) are tender and delicate.
Purchase: If buying in bunches, look for bright green, unwilted, crisp leaves with undamaged stems. If buying pre-packaged, look for small, dry leaves that look crisp and bright green.