Please write in if you have any suggestions to help this urban gardener:

For perhaps six years I've been nurturing a container garden (all pot sizes) inside an area approximately ten feet by ten feet on a rooftop outside our apartment.
Unfortunately, because the "terrace" is surrounded on the east south and west by four-story walls there is only exposure to natural light directly overhead and through a ten-foot gap the north between those buildings to the north.

I have hardly had to do any watering (especially this summer, until recently) except for the smallest pots containing house plants which I have set down on the pavers outside. I fertilize properly, I believe, and all of the pots have been prepared with proper drainage holes and drainage rubble at the bottom.

I have been able to get Oxalis, Impatiens (but not the New Guinea variety) and simple Begonias to survive and flower, although definitely not as well as they would with even a little direct sun. But almost nothing else will bloom, even if it survives as a foliage plant and sometimes reappears the next year. This would include both the obvious candidates and some which are less familiar: Coral Bells, Astilbe, Bleeding Heart, Columbine, Lamium, Liriope, Foamflower, English Ivy, Browalia, Vinca and Sweet Woodruff.

Some of these and others which seem to barely be getting by right now may need several years to get established, particularly in this unnatural environment, so I haven't given up completely on all of them, like Ligularia Dentata, for instance.
Okay, Epimedium and several perennial Gingers seem to be fairly comfortable here, although I never see any flowers.

I have pots (wooden and fiberglas) large enough to winter the plants successfully, but some perennials which are normally easy candidates for survival just never return.
I haven't even had luck with Lilly-of-the-Valley, Hostas and ferns returning the next year, but part of the reason may be unusual winter weather (unusually cold or dry or wet) conditions.
I had planted a beautiful Shadbush (Serviceberry) in a large wooden half-barrel six years ago. It blossomed beautifully the following year and bore fruit, but it never liked being there and proceded to dy a bit more each year. I replaced it this spring with an Oak-Leaf Hydrangea, and I'm hoping that guest will be happier.

I augment what does survive the summer on my roof (much of it purchased new each year) with any number of house plants, all of which seem to thrive out there.
Do you have any suggestions for plants or treatments that I might have overlooked, or could you direct me to any on-line or printed resources for this kind of situation (full shade, container garden)? I can't imagine I could be the only city gardener with this problem.

Here's a Response from Erin Bayliss, owner of Jardinière ~ Garden Services and a picture of her stoop in Brooklyn Heights.

I have had some really nice luck with my
stoop this year (all shade containers). I really went kind of nuts
with the dark heucheras, pink & white caladium, liriope, vinca and
that tropical speckled plant (pink and white varities) that you can
get at the farmer's mkts. it made for a great all-summer long
container with a nice bloom wave and pretty drought tolerant. pretty
basic and not terribly creative plant selection but made for a nice
combo and a pretty sure-fire shade collection that just kept on
pumping. very full and pretty colorful for my shady stoop. also, all
good gets at the farmer's mkt.... that is my latest thing that I am
into - promoting farmer's mkt goods in the hood.