I only have a apartment balcony for growing, this means I am always short on space. I mostly grow herbs, and veggies. This doesn't leave room for flowers. I do make an exception for morning glories. They are beautiful flowers, that almost feel magical how they only open in the morning. They also are very active vine plants, so they grow vertical, which means I save on space. Another win in my book.
Here is a picture from last year. They just go nuts!