It is important to site your winter garden in a good place for the plants, but even more important that it be where you will use it. Try to find a place close to the door so you can check your plants as you come and go. Many winter gardeners harvest dinner as they come home from work, so they won’t have to bundle up and go back out after they’re busy indoors. Tubs of herbs, salad greens, and chard, mustard, or kale on the driveway or doorstep can be harvested continuously and make many a winter meal. Tubs or pots can also be grown in a sunny spot and rotated close to the door for use.
Usually, you will be using your regular garden spot for your winter crops. No space for something new? Sometimes you can start the winter vegetables as an understory while summer vegetables are still in place. If your tomatoes are staked or caged up off the ground, try sowing shade-lovers like lettuce, spinach, or chard in between and among them. This trick has worked for me with beets and daikon radish as well. I have even sowed radish under zucchini plants near the end of the season. Collards and Kale transplants can be set out among vining squash or cucumbers where they will rapidly overtop the vines. Garlic can be planted among other crops, wherever there is a little bit of space.
Most often, you will be clearing out a bed of squash, beans, or other summer crop, working in compost, and then planting out your cabbages or Brussels sprouts or whatever. Whether you plant your winter crops piecemeal among summer vegetables, or clear the whole bed, make sure that new plantings have some compost, worm castings, or other organic amendments to fuel their growth, either as a mulch or worked into the top layer of soil around them. Also make sure that old foliage or mulch is removed to the compost pile so you don’t start the winter with pests or diseases lying in wait.
Sometimes only part of the summer garden space gets sun in the winter, so be aware of where the shadows of buildings and fences will lie. Avoid low spots where cold air collects, areas the low winter sun doesn’t reach, and areas that get waterlogged. If you can’t choose a site sheltered from wind, it is very important to provide some shelter. This is a good reason to put up a hoophouse, row cover, or cold frame. Even just a temporary bamboo fence, some branches, or straw bales can help shelter your plants from wind.
If your summer garden spot is not good for winter (if it floods, for example,) there may be a place that will work for winter only—under trees that have dropped their leaves, for example. Pots will work in mild-winter areas, but if they freeze, they will not drain, so avoid them in zones 6 and below. You can make a temporary planting bed for winter: At its simplest, it could be a rectangle made of straw bales—which provide great insulation from cold, and eventually decompose into compost for your garden. Bales could even be inoculated with mushroom culture, for a summer crops of mushrooms after your winter garden is shaded out trees. Next step up is a wooden box without a bottom, or cinder blocks laid on the ground—anything that will contain dirt. We’ve even seen gardens in plastic kiddie pools (with holes for drainage). If you want your garden to be very temporary, you can lay a tarp under the box or bales so that the soil can be gathered up, as long as water can drain out the sides. Fill your bed with a light, fast-draining soil mix, such as potting soil or heavily composted garden soil, and you are ready for a winter garden. Hoops and a plastic cover make it a greenhouse.