Garlic (Allium satvium) is a perennial that's hardy in U.S. Department of Agriculture hardiness zones 3 to 8, but it's most often grown in the garden as a fall-planted annual that's harvested in late summer. In New York, planting in late fall or early winter will yield a garlic harvest by July or August.
Garlic varieties are classified as either "hard-neck" or "soft-neck" types. Soft-neck varieties produce larger heads, and the heads store better after harvest than hard-neck varieties do. Hard-neck varieties tend to be more cold-hardy than soft-neck varieties, though, and they generally grow better in New York, where the climate ranges from USDA zone 3 in the north to zone 5 through most of the rest of the state. Soft-neck varieties might fare adequately in zone 6 along the Great Lakes shorelines and in New York City and in USDA zone 7 on Long Island.
Among soft-neck varieties, Cornell University recommends "Silverskin" and "Artichoke." Recommended hard-neck varieties include "Rocambole," "Purple-Striped" and "Porcelain."
Fall planting works well for garlic because the plants like to produce leaves in cool weather and grow their bulbs in warm weather. From the time of planting, the plant will take about eight months to produce a mature bulb, so the best planting time ranges from just after the first frost to early November. If the weather permits, planting time can be extended into December, and if the soil is workable in early spring, cloves can be planted then, too, although the mature bulbs may be smaller than those of fall-planted plants.
Garlic bulbs will rot if they're in wet soil that doesn't drain well, so plant them in a location with well-drained loamy soil; raised beds provide even better drainage and are ideal for garlic. They also grow best in a location that gets full sun.
Garlic also needs plenty of nutrition; it does best when planted in soil that's been amended with organic compost and 1 to 2 pounds of 16-16-8 fertilizer per 100 square feet of soil.
Because supermarket garlic may harbor diseases or may have been chemically treated to discourage sprouting, it's best to buy seed garlic from a local grower or a commercial seed supplier.
Break apart garlic bulbs into individual cloves, leaving the papery skin on the cloves. Plant the cloves, with their tips pointing up, about 2 inches deep and with about 4 to 6 inches between cloves. If you're planting multiple rows, space the rows 15 to 24 inches apart. After planting, cover the cloves with a thick layer of mulch; this will protect the cloves from cold injury and also help to prevent the cloves from being exposed by frost heaving.
If conditions are dry at planting time and there's no rain in the immediate forecast, water the cloves thoroughly after planting. Except during exceptionally dry falls and winters, the plants shouldn't need supplemental watering in the first few weeks after planting.