Protect Tree Trunks
Special winter protection may be required for young trees. The trunks of fruit trees and others with thin bark should be protected from rodent damage with trunk collars. I like the white, spiral-type collars since these also reflect the sun's heat, which can cause bark splitting in late winter and early spring.
Tidy Up Those Garden Beds
In the perennial bed, cut back plants to a 1-inch stub after a hard freeze. This will eliminate many insect and disease habitats while still marking the plant location for your spring work. If frost heaving is a problem in your yard, mulch perennials with 4 to 6 inches of coarse organic material after a hard freeze. It's not the cold that causes problems, it's the alternate freezing and thawing that pushes the roots out of the soil.
Established lawns will benefit from fall aeration. When soil is moist but not saturated, aerate with a hollow tine coring machine, leaving the cores laying on the surface (subsequent rains will dissolve them). Fall timing for this operation is ideal, since aesthetics are not as important now as in the spring. Fall and winter moisture will soak deep into the aeration holes, encouraging deep roots.
Last Chance to Plant Bulbs
Add more spring color to your yard by planting bulbs. Tulips, daffodils, alliums, and crocuses are readily available now, as are other more unusual bulbs. Be sure to improve the soil before planting by adding organic matter and a sprinkling of bone meal, or another phosphorus source to encourage flowering.
Secure Canes and Vines
Make sure that the canes of your climbing roses and other vining plants are securely fastened to their supports. Winter winds can whip and severely damage unprotected plants. Don't tie them so tightly that the string or twist-tie cuts into the stem. I use a length of an old nylon stocking because it stretches as the plant grows and won't cut into the stem.