When the cold winds of winter start blowing, your outdoor plants need extra protection to survive through the season. Different plants have different needs, and some plants simply can't be overwintered at all. For example, annuals such as marigolds or basil only live for one growing season, and there is nothing you can do to coax them to live longer. However, taking them time to prepare your trees, shrubs, perennials and biennials for winter will help guarantee that you'll see them bloom again next spring or summer.
Reduce the amount of fertilizer you give your plants as autumn approaches. Over-fertilization may cause the plant to put out too much tender new growth, which may get damaged by the cold temperatures or heavy snows of winter.
Water your plants until the ground freezes, or all through the winter if you live in a climate without hard winter freezes. A well-hydrated plant can better survive the winter.
Apply a layer of mulch, such as straw, shredded bark, pine needles or dried leaves, over the roots of trees and shrubs and over any perennial flower beds. Mulch helps retain soil moisture and will insulate plants against temperature fluctuations. In cold climates, aim for a mulch level of 3 to 6 inches. In warmer climates, 1 or 2 inches is sufficient.
Consider tying up any trees or shrubs with wide, branching limbs, such as yew or juniper, since the weight of snow may cause these branches to snap. Use a length of twine to bundle the branches together, wrapping the twine around the plant in a spiral. If you only get occasional or light snows, you can also simply dust off the branches after every snowfall.
Wrap evergreens such as cedar or arborvitae in burlap to prevent the needles from drying out and to discourage deer from browsing on the foliage in the winter. Leave the top of the tree unwrapped so that it can still receive some sunshine
Circle the trunk of sapling with chicken wire or hardware cloth to stop rabbits from gnawing off the bark. You can leave this protection up year round if rabbits are a problem in your area, although you should replace it once a year to allow the tree room to grow.
Cover tender plants with old blankets, sheets or plastic tarps if the weather forecast predicts temperatures lower than what is normal for your area. Remove the covering as soon as possible to allow the plants light and air circulation.
Dig up any tender bulbs or tubers that cannot survive winters in your area. These may include gladiolus, dahlias or calla lilies. Store the bulbs in a cool, dark place (such as a basement or root cellar), wrapped in newspaper or buried in sand or sawdust. Replant the bulbs in the spring.
Bring tender perennials grown in containers indoors. Geraniums, for example, may be brought inside in the winter and grown as houseplants; place them in a south facing window and watered them regularly. Fuchsia go dormant in the winter, and should be stored in low light conditions with only occasional water, just enough to keep the roots hydrated. Some herbs, such as parsley or rosemary, may also be grown indoors in the winter.