Answer: Start with a good grade of potting soil and underplant with bulbs for a late winter, early spring surprise. Use Crocus, Narcissus, Hyacinth and tulips. Then plant pansies, dusty miller, chrysanthemum and primrose. In the fall you can add ornamental kale for a color change. Evergreens perfect for windowboxes include heathers and the trailing vinca minor. You might also plant Erysimum and Hellebore for splashes of color. Evergreen ornamental grasses such as Carex, Japanese sedge grass, Liriope, or Japanese bloodgrass.
Hope this gives you some ideas!
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