Answer: A windy situation will be very stressful on plants, especially those in containers because the soil will dry out quickly. Japanese maples would not be a good choice, they really need a sheltered spot during the winter as well as an evenly moist soil. For winter hardiness, you should look for plants at least one zone hardier than you normally need, or zone 5. Ornamental grasses might be a good choice. For evergreens, based on my experience junipers would be more likely to survive than the arborvitae. For a small tree you might try a smaller growing variety of crabapple, these are fairly tolerant of a range of conditions with good winter hardiness as well.
For the best results, use the largest possible containers (be sure to check the weight restrictions on your balcony) to help insulate the roots from both heat and cold and to provide as much root space as possible. The containers must have drain holes in the bottom. Use a good quality potting mix formulated for container plants. And, you should plan on watering as needed to keep the soil evenly moist (not sopping wet, not dried out) any time it is not frozen. I hope this helps with your planning.
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