Garlic is a species in the onion genus, Allium. Garlic has been used for both culinary and medicinal purposes. Medicinal use of garlic from University of Maryland School of Medicine. Garlic is easy to grow and can be grown year-round in mild climates. Nearly all of the garlic in cultivation is propagated by planting individual cloves in the ground. In cold climates, cloves are planted in the fall, about six weeks before the soil freezes, and harvested in late spring. Cold hardy USDA zone 4-9.