The tender flesh has a high water content, a mild flavor and doesn't require long cooking. Summer squash is best from early through late summer, although some varieties are available year-round in certain regions. Select the smaller specimens with bright-colored skin free of spots and bruises. Summer squash is very perishable and should be refrigerated in a plastic bag for no more than 5 days. Summer squash are high in vitamins A and C as well as niacin.
Winter squash have hard, thick skins and seeds.
The deep yellow to orange flesh is firmer than that of summer squash and therefore requires longer cooking. Though most varieties are available year-round, winter squash is best from early fall through the winter. Choose squash that are heavy for their size and have a hard, deep-colored rind free of blemishes or moldy spots. The hard skin of a winter squash protects the flesh and allows it to be stored longer than summer squash. It does not require refrigeration and can be kept in a cool, dark place for a month or more, depending on the variety.