I live in an apartment in the city (located roughly central east-coast of US) and really miss my father's garden in the suburbs. As such, I have figured out a scheme for window boxes that has allowed me to grow some nice herbs (basil and oregano). I would like to make this work with a similar set-up for flowers on my other window sill. I have grown poppies before in the ground and they are just so beautiful and fun to grow that I would like to try to grow them in my current situation. Now, I know they get very big and typically need a lot of space to grow to their full size, but I was wondering if it would be possible to grow a single poppy plant to at least a medium size in a standard window box (say roughly 500 cubic inches)? If not, what flowers would you suggest to grow given my circumstances?
NOTE: My windows get pretty good sunlight throughout the day. After about 4 pm, there is a tree that kind of blocks the sun but for the most part light still makes it through.