What not to grow: anything that is not hardy to zone 0a. Typically our environment is dry, We only get about 6 inches of rain a year and the humidity is low. This means our gardens are dry. Things that need a lot of water don't do well. We do get much sunlight. 270 degrees from sunrise to sunset in June. You may find a micro climate that works well for warm, water loving items, but it probably won't be at the community garden.
If you insist on trying some of these items at the garden. Use a row cover or a cold frame or some sort of plastic cover to protect your crop. Even a clear plastic bag secured and supported will go a long way to keeping your plants warm and moist.
Unless you have a greenhouse or other area with the correct micro-climate you will not have much success with
or any other vegetable or herb that requires hot temperatures and a longer season to mature. Parsnips and corn are possible but don't give a high yield.