Butternut squashes are often available from September until the middle of December. However, since many foods arrive from South America, they can easily be found around in different seasons.
It is best to buy well-grown whole butternut squash. Look for a mature product that features a fine woody note when tapping, and is heavy in hand. The stem should be stout and firmly attached to the squash. Avoid those with a wrinkled surface, spots, cuts or bruises.
Once at home, a well-ripened squash can be stored for many weeks in a cool, humid-free, well-ventilated place at room temperature. However, pre-cut sections should be placed in the refrigerator where they will keep well for a few days.