Creating food (which restores energy) is the most important endeavor in the game. More food means more energy, which means more playtime. (Running out of energy may not completely stop you from playing the game, but bopping back and forth to Hell isn't much fun and ruins your Mood, so there's not much point.)
Early in the game, the most accessible food to create is the humble Sammich. Creating sammiches requires Meat (from Piggies), Grain (from Chickens), and Allspice (from Spice Plants). To combine them, you'll need EZ Cooking I, Cheffery I, and Spice Milling, plus the tools which go with them (a Knife & Board, Frying Pan, and Spice Mill, respectively).
With nothing more than the base skills, you'll regain barely more energy than you put into it (petting and nibbling a piggy, squeezing five chickens, harvesting spice, and putting them together is likely to run you almost 20 energy, compared to the 29 you get from eating the sammich), but it's still over parity, so the more you make the better off you'll be.
Even better, learning Animal Kinship skills and higher levels of the base skills will dramatically improve your effectiveness. Bigger harvests, lower energy costs, and access to more powerful recipes will have you brimming with energy in no time!
Try Zog's Glitchy Tools, a collection of data gleaned from the Glitch API. Specifically, the locations page shows details of Vendors, Trees, Resources, etc and clicking on a specific one will tell you the closest location and how to get there from your current location.
Best Answer
Corn takes six hours to grow. It does depend on what crop it is.
As far as I can tell, you've got a bit of leeway in the public gardens, but not a heap.