Ask Mr. Smarty Plants

The Lady Bird Johnson Wildflower Center is dedicated to the care and propagation of plants native not only to North America but to the area in which the plant is being grown. Plants accustomed to the climate, rainfall and soil of an area will need less water, fertilizer and maintenance. Syringa vulgaris, common lilac, is native to southeastern Europe and therefore out of our range of expertise.However, a probably more compelling reason for you not to plant a lilac in a pot on your balcony is that a lilac bush is just way too big. They can grow to 8 to 15 feet tall and 6 to 12 feet wide. Worse, they only bloom about 2 weeks in the Spring. 

Without the protection of being in the ground, the roots of a potted plant are very susceptible to freezing and you likely don't have room to bring your pots in during the winter to keep them in dormancy. We would recommend that you go to a nursery and ask for advice on what they have that will accept your planting conditions. They probably won't be native plants but since it's unlikely that potted plants on a deck will escape cultivation and invade native habitats, we doubt that is a problem.