Your first major decision should be to figure out the purpose for your garden; from there, you can choose the right plants for your window box.
Ornamentation
Most people's window gardens exist purely to spruce up their home and neighborhood. You may be satisfied to have just one burst of color in the spring and then allow trailing plants dominate the window garden for the remainder of the growing season.
For permanent window boxes and year-round greenery, a "winter interest" window garden can include evergreen such as:
Dwarf Alberta spruce, bristlecone pine, mugho pine, and small cacti
The dwarf evergreens grow at a rate of an inch per year, so they are ideally suited to long-term window gardening. Finally, trailing plants (the kind that grow down your window) are great for year-round greens.
Some examples are:
Ivy, myrtle, creeping Jenny, sweet potato vine, and vinca
Some spring flowers include:
Pansies, tulips, daffodils, crocuses, primroses, lilies, and violas
However, if you wish to continue seeing flowers through the summer, plant:
Geraniums, lavender, impatiens, salvia, petunias, daisies, begonias, zinnias, fuschias, and
nasturtiums
(Nasturtiums have an added bonus for urban gardeners: their leaves and flowers are edible and add a peppery, cress-like taste to salads and sandwiches).
If it's fragrance you're after, choose the following fragrant plants:
Sweet basil, mint, lemon balm, lemon verbana, lemon thyme, dill, peppermint, spearmint, pineapple mint, sweet alyssum, nicotania, lavender, jasmine, and moonflowers
Many vegetables can be grown in window gardens:
Lettuce, cabbage, tomatoes, beans, peas, scallions, kale, and peppers
You can grow herbs too, such as:
Sage, thyme, rosemary, basil, parsley, marjoram, mint, dill, hops, sorrel, lemon balm, and bay
