Squash, like other fruits and vegetables, contains bacteria and enzymes that will break it down with time, destroying its flavor, color and texture and reducing its nutritional content. While you do not have to cook squash before freezing it, you should blanch it to stop the activity of these enzymes and bacteria. It is easier to freeze summer squash without cooking. Winter squash should be cooked first because you'll need to remove the squash from the skin before freezing.
Wash the squash in cool running water. Use a soft kitchen brush to remove any sticky dirt or other residue.
Lay the squash on a cutting board and slice off both ends with a sharp kitchen knife. It is only necessary to remove about 1/4 inch from each end.
Fill a large pot with water and place it on high heat until it comes to a boil. Leave enough space in the pot for the squash.
Slice the squash into 1/2-inch pieces, cutting up only the amount of squash that will fit in one pot of boiling water. If you leave cut squash for more than 30, it will begin to discolor.
Drop the squash into the boiling water, cover and blanch for three minutes. While the squash is blanching, fill a large bowl with water and ice and set it aside.
Scoop the squash out of the pot with a slotted spoon and immediately transfer it to the ice water. Submerge it completely and allow it to sit in the water for five minutes.
Drain the squash in a colander and pat it dry with paper towels.
Place the squash in a vacuum freezer bag or zipper bag, making sure to remove as much air as possible from the bag to prevent freezer burn.