In the midst of winter there just isn't much flower power to hold one's interest in the garden. I actually rely very little on flowers for visual interest in the garden. Texture is king. Contrasting shapes, surfaces, materials, plant shapes and colors all create an exciting scene. Again, winter is when the blanket of green is pulled back revealing the true structure of a garden. If it's monotonous or one-dimensional, then think about contrasting shapes and textures to bring it to life.
Above (clockwise), Euphorbia biglandulosa (Gopher plant) with it's Dr. Suess succulent leaves separates nicely against the caramel colored dried (okay, dead) purple fountain grass, which is treated as an annual in our USDA zone 8. A blue filled sky and graphic pecan clusters, ipe wood deck adjacent to red crushed granite gravel, the magnificent Agave americana (Century plant) is always a mid-winter stunner and the glaucous blue leaves pop out against the peeling cedar fence. And of course with sky there is earth and water to really round out the complementary contrasts.