Guerrilla gardening refers to planting food crops on land you don’t strictly own or in places that don’t look like gardens.
I like to think of guerrilla gardens as sort of like hidden caches of food, in a way.
Guerrilla gardening can be used in both the city and in rural areas. The basic idea is to plant vegetables or fruits in out of the way areas, where hopefully there is little chance of discovery. Abandoned city lots are sometimes used, as are edges of farm fields.
Obviously, you don’t want to use plants that need a lot of upkeep. Stick with things like potatoes, berries, onions, and squash. Sunflowers are another good one. No, you likely won’t be able to grow enough food to sustain you, let alone an entire family, through guerrilla gardening. But it is a great way to help augment your normal gardens.
This is also a way to grow food at your offsite retreat if you are unable to be there full-time to tend to things.
What you might consider doing, if you expect a lengthy trip should you need to bug out, is plant some stuff along your route. Of course, there are no guarantees that things will be ready to eat, or even still present, during your bug out. But, I can guarantee nothing will be there if you don’t plant it ahead of time.