Networking takes the guess work out of the process. As an added bonus, you'll spread the word about the exciting project that you're working on. The city real estate department can tell you who owns the vacant lot, warehouse yard or old parking lot you've been eyeing. They may even give you a tip on city property that is sitting vacant. The Parks department may have suggestions on park land that is rarely used.
Public works can help with locating a water source.
They might consider giving access to a nearby fire hydrant. The Public Library can help. Ministry of Agriculture supplies soil sample kits, to test for nutrients. Try soliciting neighbourhood churches, seniors groups or garden clubs to donate tools, wheelbarrows and hoses. Youth groups or high schools might pitch in to build a shed.