Harvested when fully ripe, the average acorn squash weighs from one to three pounds. Any larger and you risk getting a dry, stringy squash. It's difficult to judge an acorn squash by its outward appearance. It should feel heavy for its size with smooth, dull skin and absolutely no soft spots. Shiny skin indicates it was picked before fully mature, unless the producer has applied wax. Look for some partial orange on the skin as a sign of maturity. On the other hand, too much orange coloring on the skin indicates an overripe squash which will be dry and stringy. A good balance between green and orange coloring is optimum. When comparing, know that lighter weight ones have lost moisture through the skin and will be drier.
Winter squash will last up to a month in a cool (50 to 55 degrees F.) dark cellar or storage area, but only two weeks in the refrigerator. Ideally, only cut or cooked acorn squash should be refrigerated. They will suffer chill damage at temperatures below 50 degrees F. Dry hot air will cause loss of moisture, resulting in a shorter shelf life. Squash with a bit of the stem still intact will help slow down moisture loss. Plan on using acorn squash within two weeks of purchase, since you never know how long it has already been in storage and under what conditions. If you grow your own, you have more control and thus a longer storage time (two to three months). Once cut, wrap raw pieces in plastic wrap, refrigerate, and use within four days.
Cooked acorn squash can be sealed and refrigerated up to four days. Before freezing, acorn squash must be cooked. Cook squash and remove the pulp from the skin. You can leave it in chunks or mash it. Place in airtight containers and freeze ten to twelve months at 0 degrees F.