Whenever your compost heap isn't frozen, attack it with a mattock or turning fork, and mix in all those broccoli stems and orange rinds leftover from holiday cooking. Cold temperatures always make decomposition go slow, but the two Ms, moisture and mixing, will insure that your compost starts cooking first thing in spring.
Midwinter is the best time to prune healthy trees. Fruit trees such as apples, peaches and plums need pruning every year, but ornamentals need less attention. Removing dead branches, low limbs that interfere with human movement, and wood that is split or damaged is usually sufficient.
As new seed and nursery catalogs arrive in the mail, set them aside in one place. Then update your collection in one fell swoop, sending the oldies to your recycling bin. As you study new catalogs, use sticky notes to mark pages where you see things you want to order.
Check for Heaving
Freezing and thawing of soil often causes pansies, dianthus, chrysanthemums, and other plants that are set out late in the year to heave up out of the ground. When you notice plants sitting unusually high, gently press them back in place. Usually they will recover and grow nicely in the spring.
Keep containers planted with spring-flowering bulbs or hardy flowers in an unheated garage or other protected place where they will be cool but will not freeze. If you have a wagon or garden cart that's not being used, use it to shuttle plants outdoors to enjoy the sun on mild days.