Yes, trees and shrubs can fulfill that need – evergreens, of course, and also trees like Hawthorns, with their bright red berries that persist until spring, and shrubs like red- and yellow-twig dogwood with bark that is striking against a backdrop of snow.
But don’t feel limited to plants. I have one very durable blue metal chair that stays out all winter long, and it brings me cheer. I’ve seen brightly painted garden walls and fences, furniture, pots, sculpture, and all sorts of other non-plant-material garden elements that stand out and provide color between November and April. What about you? What’s “blooming” in your winter garden? Now is the time to gaze out the window and think about where you might want those bright sparks that bring joy and hope on a cold, grey winter’s day.