Photo: Galanthus naturalized in woodlands (courtesy of Brent and Becky's Bulbs)
These bulbs are the early birds. Give them a week of warm weather in the 50's, nights slightly above freezing, and little to no snow cover. A beautiful flowering patch of winter aconite (Eranthis), snowdrops (Galanthus), glory of the snow (Chionodoxa), or early crocus appears in January and February in USDA zone 6 and 7.
These "special" bulbs naturalize and come back every year. Bulbs are planted in the fall and are purchased from bulb emporiums on-line or through mail order nursery catalogues. Two personal favorites for purchasing bulbs are Brent and Becky's Bulbs in Gloucester, VA and van Bourgondien's Bulbs in Dix Hills, NY.
Dec. 21, 2009 conversation with Brent Heath: he identified additional early flowering gems in the winter garden in zone 6: The earliest daffodil is Narcissus 'Rijnveld's Early Sensation' with golden yellow opening in mid-to late January in zone 7. Flowers last and last in the cold winter weather. Many species crocus bloom in February and March. Crocus ancyrensis 'Golden Bunch' opens with small tangerine yellow blossoms, one of the earliest to bloom in the winter season. Other early bird crocus species are C. imperati and C. tommasinianus.
Muscari armeniacum 'Christmas Pearl' bears 4-6 inch double blue flowers beginning in late February.