Flowers referred to as bulbs earn this moniker because of their roots that store nutrients needed for next year's growth. "Bulb" is a generic word for plants that grow from these bulbous organs, and include daffodils, tulips, crocuses and many more. While different flowers' roots look similar to one another, their blooms are quite diverse and represent every color of the rainbow. Some bloom in the summer or fall -- others reach full radiance in the winter or spring. Although bulbs have a reputation for being easy to grow, many still need to be insulated against winter's chill. All bulbs have a temperature limit; dip below it, and the plant can't survive.
Some that require cold protection go dormant and can be dug up and stored in a dark, dry place that's ventilated and covered. Just wait until foliage yellows, dig it up and remove leaves and dirt so only the bulb remains. Dry it on newspaper for two weeks. In a wooden or cardboard box or clay pot, spread out bulbs in one layer so they don't touch (this prevents any rotting from spreading). Lastly, cover them with peat moss, sawdust, sand, perlite or vermiculite until they're ready to be replanted.
Other bulbs can stay in the ground and withstand cold temperatures that slightly exceed their limit if protected. Simply cover the ground where your bulbs are planted with loose packing materials after the soil has frozen. Prairie hay, reed canary grass, evergreen boughs, marsh hay and other options work well.