Garlic is planted in the fall preferably before frost but if necessary as long as the ground is workable. You detach the individual cloves from the bulb a couple of days before you plant them. The most common recommendation is to plant the cloves 2-3" deep with the pointed end up about 6" apart and in rows 36" apart. One group of growers suggest 4" deep and we use a university researched system of 3" deep 6" apart in double rows: 6-8" between the first 2 rows and 18-30" between the next double row. I like this method because it makes care, watering and weeding much easier. After planting and fertilizing (Bone meal in the furrow and a light dressing of manure on the surface) we heavily mulch with hay from goat pens. If you don't have any of these marvelous creatures, you can use almost any mulch. Some growers recommend removing the mulch after the plants emerge in the spring but we prefer to leave it. It radically ups the soil moisture and nearly eliminates weeds. The 2 worst enemies of garlic are dry soil and shade even from weeds.
Harvest when the bottom leaves begin to turn brown. This is a bit scary as you think that if you leave the bulbs in the ground longer they'll get bigger—not usually true, and the garlic is easier to clean if it's greener. Some varieties mature more quickly than others. For example, Spanish rojo has to be harvested quite a bit before Ukranian.