There are three types of bulbs. Hardy bulbs refer to those that will survive cold climates. Most spring flowering bulbs are hardy. Examples of hardy bulbs are tulips, hyacinths, crocuses and daffodils. Semi-hardy bulbs are hardy in milder climates, but can not handle temperatures below zero. Some examples of semi-hardy bulbs are paper whites, ranunculus, and anemones. Tender bulbs are those that can't tolerate freezing. Tender bulbs may be left in the ground in warm climates, but in climates that have freezing conditions, they must be dug and stored indoors. Tender bulbs include dahlias, tuberous begonias and calla lilies. Corms, tubers and roots may also be classified as tender bulbs.
Dig up the bulbs. Gently loosen the soil surrounding the bulbs with a spade. Dig a few inches away from the plant so you don't accidentally cut into the bulb.
Wash bulbs carefully with a hose and a gentle stream of water.
In a well ventilated room, place the bulbs in a single layer on newspaper or in flat boxes out of sunlight. The ideal temperature for drying is 60 to 70 degrees. Dry the bulbs for two to four days.
Dust the bulbs with an insecticide-fungicide labeled for bulbs. Throw away any bulb showing disease or insects. Put the bulbs in plastic bags with small slits cut in them for ventilation. Pack them loosely with vermiculite, dry sand or sphagnum moss.
Label each bag with the name of the flower. You can even label each bulb directly on its surface with black permanent marker.
Store bulbs according to their individual needs. Each type of bulb will require a different storage temperature and humidity. Local university extension offices have storage temperature and humidity guidelines.
Check on stored bulbs regularly. Throw out any that are showing rot, disease or insects.