Zone 7 is characterized by mild winters--in which the lowest temperatures dip down to 0 degrees Fahrenheit at night--and warm, temperate summers. Because winter temperatures are so mild, it is possible for Zone 7 gardeners to extend their gardening all winter long if they select the right varieties of plants and protect them from freezing. This can be accomplished through mulching or growing plants in greenhouses.
Position your garden so that it receives maximum sunlight and heat as well as protection from winter winds. Sunlight is a major limiting factor to winter gardens, especially in the shortened days of winter. A good location for a winter garden is near the south side of a wall or building. A brick wall will absorb heat during the day and release it at night to create a warmer microclimate around your garden. The wall will also shield the garden from cold temperatures and freezing effects of wind.
Break up the soil with a rototiller to a depth of 6 inches. Add 4 inches of compost to the surface of the soil and mix it with the soil by passing a rototiller over the soil again. Compost will add nutrients to the soil while improving drainage. Drainage can be a big problem in late winter and early spring when rains dump additional water onto the garden. Poorly drained gardens can waterlog plants and promote root rot.
Select plants that are cold-hardy for winter temperatures. Plants that grow well in cold weather include root crops such as carrots and radishes or leafy vegetables such as kale and cabbage. Plant these plants as seeds in early to middle fall, or start them in seed pots and transplant them into your garden well before the first frost date of the fall so they have the chance to become established.
Mulch around plants to keep frost off the roots and prevent the ground from freezing around them. Mulch works very well for root crops such as carrots, radish and turnips.
Cover plants with floating row covers, upside down plastic milk containers with the tops cut out, or mason jars turned upside down to create temporary miniature greenhouses during cold winter days and nights. Never leave plants covered for more than a few days. These miniature greenhouses can warm plants, but they promote poor air circulation and can cause disease if left on for too long.