Before starting your tedious task of planning, consult with your homeowners' association or management company. More often than not, the management of your townhouse or the association will have certain rules in place regarding exterior additions -- including landscaping. Restrictions may include those on height, native status, placement or even color. While this may limit your choices, think of it as a good thing: if there are restrictions, you know what to avoid, which can help you with where to start.
Being able to complement your neighbors while adding a hint of uniqueness to your townhouse is another challenge. You want your townhouse to stand out without looking out of place. For example, if your row shows a trend of purple beach morning glory (Ipomoea pes-caprae), a native plant hardy in U.S. Department of Agriculture plant hardiness zones 9 through 11, break it but choose plants that complement the flower color of your neighbors' vines. In this example, choose yellow flowers because yellow complements purple. A 5-foot tall, lemon-yellow Rock's Kaua'i hibiscus (Hibiscus calyphyllus), hardy in USDA zones 9 through 11, would complement your neighbor's purple morning glory while adding height.
The small space may seem like a formidable opponent, but you can play tricks on the eye to expand it. Repetition is a major factor in elongating and expanding the small space you have to work with. Since potted plants are your friend for townhouse landscapes, stick with the same design and color, but different sizes. For in-ground plantings, focus on plants with lush foliage. For example, choose a lush, native groundcover such as 'Ilima papa (Sida fallax), hardy in USDA zones 10 and 11. This low-growing variety of 'ilima reaches only 6 to 12 inches tall. Beach vitex (Vitex rotundifolia), hardy in USDA zones 7 through 10, is another Hawaiian native that reaches 1 to 2 feet tall. This fast-growing groundcover's foliage is silver-tinged with a spicy fragrance. The thick, rich foliage of these groundcovers can blend your veranda area seamlessly with the lush Hawaiian landscape to create an endless array of flora.
Landscaping isn't all about plants, it also entails hardscaping features such as rocks, paths, fountains and other features. These features can add functionality as well as aesthetic value to your overall Hawaiian landscape. A small fountain -- a wall fountain or tabletop fountain -- can add a tranquil touch with its relaxing sound. Uplighting around your front or rear patio area can highlight certain plants or architectural details of your townhouse while setting you apart from your neighbors.