In cold climates, cloves are planted in the Autumn about six weeks before the soil freezes.

http://en.wikipedia.org/wiki/Garlic

In cold climates, cloves are planted in the autumn, about six weeks before the soil freezes, and harvested in late spring. The cloves must be planted at sufficient depth to prevent freeze/thaw which causes mold or white rot Garlic plants are usually very hardy, and are not attacked by many pests or diseases.