When we first became interested in producing our own food, we guerilla gardened. Abe (always the adventurer) discovered a floodplain behind the apartment complex we lived in. Getting there involved a walk through the woods, a healthy respect for copperheads, and a balancing act across a creek (good practice, maybe?). But it was land no one was using, and our narrow third floor balcony hardly had enough sunlight to grow a few cherry tomatoes. We cleared a small patch of ground and dug in.
It wasn't exactly an ideal garden site. The spot was a trek from our apartment. The land was swampy, and we got itchy red bumps to prove the gardening bug wasn't the only one to bite us. There was the chance of falling in the creek (Sorry, Dad). The area's deer had also discovered this little wilderness and helped themselves to most of what we planted. We may or may not have been voilating the city's flood plain regulations. Still, we enjoyed a few skinny carrots and our first real taste of vegetable gardening.
Now, two years too late, I'm glad to have come across a land access toolkit by the East Bay Urban Agriculture Alliance. They provide great advice on negotiating land use for those who might not already have access to a garden site.