Answer: There are many spring blooming bulbs that can be planted in the fall. You could consider daffodils, crocus, early snow crocus, snowdrops, grape hyacinth, Iris reticulata, Scilla sibirica and winter aconite for starters.
Winter blooming flowers are few and far between, but the hellebores bloom in very early spring, as does Pulmonaria.
For winter color, most gardeners rely on evergreens, bark color and branch pattern of deciduous trees and shrubs, and the overall layout or "bones" of the garden as marked by paths, pergolas, fences, hedges, and so on.
Many gardeners tend numerous house plants and start seedlings indoors in the spring to keep their green thumbs busy during the winter, too.
I hope this gives you some ideas.
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