Inland Northwest, High Desert
Mulching is a good way to protect roses and tender perennials in winter, but don't mulch too soon. The mulch should keep roses and tender perennials cold, not warm. Keeping them cold prevents the freezing and thawing that will heave the plants out of the ground. Wait until the ground is frozen before you mulch.
Even though the temperatures are dropping, evergreen shrubs and trees, especially, need to be watered if Mother Nature isn't obliging. Deep watering now will help those plants survive the cold, drying winds of winter. The healthier the plant going into the winter, the more likely it will survive.
Thanksgiving is the day to prune the roses, but anytime into early December is fine. We almost always enjoy a fine early winter day on that holiday, perfect for pruning. Prune the roses back to knee height and throw the canes in the trash so not to spread any disease. Pick up and destroy any leaves you see in the garden, too. We don't want any insect eggs or fungi hanging around to cause trouble next spring.
Add Manure Now
Before the ground freezes, spread a layer of manure, leaves, or other organic matter over your annual and vegetable garden beds and till it under. Adding organic matter now will help the soil drain faster in spring, and the organic matter will slowly decompose during the warmer days of winter. By spring you'll be ready to plant.
It's time to give all the indoor plants a bath - especially if you've brought some of them in from outdoors. In the tub, mix up some dishwashing liquid in a bowl of warm water and sponge off every leaf and stem. Rinse with a weak tea solution. That should put a damper on any bugs that had designs on your indoor garden.