Plant your garlic bulbs just after the first frost of the year. Depending on what zone you live in, that would be somewhere between October and November. If you live in an area where you do get some snow, it is a good idea to cover your planted garlic bulbs with hay or some other light mulch to give them a little bit of protection from the elements. You should be able to see the tops of the garlic peeking out of the soil in early spring. This is the time for harvesting. Use a pitchfork to gently lift up the soil around the garlic and then use your hands to remove it.
Onions thrive in cooler temperatures. Although you should not plant onions in the fall in cold climates, you can plant them in January or about eight to 10 weeks before the last frost. You can plant onions from seeds or from sets. Most people have better luck when it comes to planting sets instead of seeds, which take a long time to germinate. If you live in a zone that does not get any frost, you can plant onions in the fall for a winter harvest.
Plant your spinach in the fall. Spinach prefers the cooler temperatures of fall and early winter. Spinach can handle some frost. One of the keys to planting spinach for a winter harvest is to chill your seeds in the refrigerator for two weeks before you plant them in the ground. This helps get your seeds accustomed to the cool weather and will help seeds that do not germinate in the fall survive winter and sprout for a very early spring harvest.
Carrots and other root crops such as turnips and parsnips can be planted in a winter garden. Plant the seeds in the fall while the ground is still somewhat warm and definitely before the first frost. Because of the cooler temperatures, the plants will grow slowly and will continue to grow throughout the winter months. The vegetables should be ready in February or March depending on what zone you live in.