Answer: These conditions bring to mind the climate of the high desert! You have a fine opportunity to have a unique, exotic garden in the heart of New England! The most limiting factor in your situation is winter temperatures. Even the most hardy of plants and shrubs don't survive severe cold in exposed containers. In nature they count on the insulating effects of a large volume of soil to keep roots from freezing, so you'll need to duplicate that kind of insulation with thick layers of straw wrapped in plastic. The other aspect of winter protection is from desiccating winds. Again, plants grown in the ground are less likely to dry out in winter winds, so you'll have to wrap your tall shrubs in burlap for the winter. In the spring, gradually expose them to sun and wind so they don't go into shock.
There are zillions of annual plants and flowers that will thrive in containers - choose any that are labeled "grow in full sun" (i.e. zinnias, cosmos, snapdragons, portulaca, geranium, hibiscus, etc.), most vegetable crops. Most sun-loving hardy perennials can also adapt to containers (coneflower, rudibeckia, ornamental grasses, etc.). Container grown plants often need to be watered on a daily basis, so make it easy on yourself and use self-watering containers or hook up a simple drip irrigation system.
Let me recommend a great book on the subject: Container Gardening For Dummies by Bill Marken and the Editors of National Gardening Magazine (for more info, check out http://www.dummies.com). This takes you through the whole process of design, planting, care, etc. There may also be a container gardening club in Boston for you to hook up with. Best of luck and have fun!
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