Some iris bulbs are sensitive to frost and need to be stored above freezing temperatures to survive. Iris bulbs that are stored for the winter can be planted or transplanted back in the garden once the danger of frost has passed.
Use a trowel to dig the iris bulbs up from the ground, before the first frost of the season hits.
Lay the bulbs on cheesecloth or burlap in a dry, cool place. You need to make sure they completely dry out before you store them. Once they are dry, scrub off any remaining dirt and leaves with a towel. If the bulbs are damaged at all, sprinkle a bit of sulfur on them to prevent any rot. Separate out the damaged bulbs and do not store them with the healthy bulbs.
Store iris bulbs in three ways. Once they are completely dry, put them in a sealed paper bag with peat moss surrounding the bulbs. Store the bag of bulbs in the crisper drawer in the refrigerator (at about 35 F) over the winter. Remove everything from the crisper drawer except the bulbs, since fruits and vegetables can emit ethylene, which kills iris bulbs. Store the damaged iris bulbs in a separate paper bag. Keep the bags sealed.
Store the Iris bulbs in a cool, dry and dark place like a pantry or dry cellar if you don't have room for the bulbs in your refrigerator. Store them in paper bags with peat moss, and separate the damaged bulbs from the good ones. Keep the bags sealed.
Consider growing the iris bulbs in pots in your home if you want to provide some color to your household and don't want to thwart their growth at all. After digging them up from the ground, transplant the bulbs to growing containers. Place them in a sunny window, or even outdoors on the patio on warm days when the there is no chance of frost. Make sure to care for them as usual with regular watering.