Fall is the best time for planting garlic. If your winters are long and cold get them in the ground in mid September. This allows the bulbs to put out roots before winter weather sets in. The hard neck varieties do best in my zone 4 growing season (1a in the western garden book). If you are wanting to plant Elephant Garlic it does not do well in cold areas without some sort of covering. I have used a 4 inch bed of straw placed over an outdoor planting, but usually suffer a fifty percent loss due to winter kill. The past few years I have only planted the Elephant Garlic in the Greenhouse with a thick layer of mulch and it has done extremely well.
Plant individual cloves about 3-4 inches apart with the root side down, pointed side up. Garlic likes loose, viable soil so add plenty of organic matter and till into the soil before planting. Water well and cover with a thick layer of mulch.
If you do not have a greenhouse try planting garlic in a large cold frame
garlic is one of the first plants in my greenhouse to break ground in the early spring
(we feed the tender weeds to the hens so I just let them grow freely until we start planting tomatoes)
Egyptian or Walking Onion bulbs should also be planted in the fall. Simply break them apart and plant the individual bulbs with a 3 inch spacing. Do not dig up the mature plant. It will winter over, multiply underground, and send up new growth in the spring. Dig the onions for table use before they send up the long flower spike. The bulbs become pithy as they put their energy into producing the tiny new plants at the end of the spike. If left unattended the spike will eventually fall over to the ground and the onions will plant themselves.
Dig up the whole plant of bunching onions. Divide into clumps of 6 to 8 onions. Cut back the tops and replant. Potato onions can also be planted this time of year. Shallots are usually planted in the greenhouse to prevent winter kill, or if I plant them outside, I wait until early spring. You can purchase garlic at the grocery store and plant. Shallots and Jerusalem artichokes purchased at your local store usually do well also. The onions from the store are mature and if planted will grow fresh green tops, but they are only editable for a short time in the spring before the onion produces a seed head and the stems turn pithy. They make a beautiful statement in the garden however.