Sunflower Serendipity 0
You can grow sunflowers in pots.
It started by accident. My friend put sunflower seeds from the pet shelf in the grocery store in the flower pots as a treat for the cardinals (the ones with wings, not the ones with hats). A couple of weeks later, unfamiliar sprouts started to compete with the petunias and impatiens and portulacas; a guess plus a web search convinced us they were sunflowers, so we transplanted the strongest ones to a great big pot to see what would happen.
Sunflowers happened. The deck will be ablaze with them in a few more days.
They need little care other than frequent watering; they are very thirsty.
I guarantee that we have the only deck in the neighborhood with honking great five-foot tall sunflowers on it.