Window boxes were supposedly invented in Venice to contain aromatic plants that repelled mosquitoes (and probably because garden space was so minimal in Venice). Hanging plants like nasturtium and ivy geranium are traditional window box plants because they do not obscure scenery or sunlight. Scented geraniums are also popular because they are be so strongly aromatic.
Scented geraniums are of the Pelargoniuim genus, so are related to ivy and common geraniums, but are a mix of a few different specie and hybrids. Their foliage can smell like rose, lemon, orange, apple, strawberry, ginger, mint or other herbs or spices. Specialty geranium growers may have nearly a hundred varieties to choose from, which is less than half of the known varieties.
Not many scented geraniums bloom with impressively colorful flowers. However, many have interestingly textured, colorful and lobed foliage that might be velvety or even raspy. The more compact varieties stay less than a foot tall, and spread laterally very slowly. Others have longer but limber stems that lay low as they spread like sloppy ground cover. A few stand upright as tall as five feet.
Out in deserts, where vegetation can be a scarce commodity, cacti, agaves and yuccas protect themselves from grazing animals with thorns, spines, caustic sap and distastefully textured foliage. None of these defense mechanisms is perfect. They only need to be better than what the competing specie are using. Many plants find that objectionable flavor and aroma work just fine for them.
The funny thing about the objectionable flavors and aromas that some plants use to discourage grazing animals from eating them, is that these same flavors and aromas are what make so many of them appealing to people. It is ironic that what was supposed to make them distasteful to some is what makes them tasty to others. Yet, it also gets us to perpetuate them in our home gardens.
Mint, thyme, lavender, rosemary and sage, which all happen to be in the same family, are culinary herbs that also work well in the landscape. The mints need the most watering, and containment if their innate invasiveness is a concern. Thymes need less water, and some are nicely aromatic ground cover for small areas. Lavenders and rosemaries can survive with minimal watering here.
Both rosemary and sage are popular for landscaping anyway. Rosemary is most commonly grown as a ground cover that cascades nicely over low retaining walls, but some cultivars are shrubby. Sages are extremely variable. Some are showier than they are useful in the kitchen, with elegant and colorful flower spikes. Others are too strongly aromatic to cook with, but are used as incense.
Fennel and chamomile are often grown in vegetable gardens rather than out in the more refined parts of the landscape because they can get somewhat awkward. Fennel has such nice feathery foliage at first, but if not harvested, it gets tall, and then yellows after bloom. Chamomile gets tall and open in bloom, and then no one wants to ruin it by harvesting all the flowers if it looks too good. Chives are easier to work with. They have so many leaves that no one misses a few taken for the kitchen.