What size of garden you build depends on how much space you have, and how much time and energy for maintenance. Even if you have unlimited space, you are better off starting with a small space that you can keep up with (and expanding later), than taking on too much at the start and having it end up a disappointing jungle of weeds.
Pots and Planters
No soil, or horrible soil? Then you can grow a wide variety of food in pots and containers, anything from black plastic nursery pots to large wooden planters. I spent 13 years in a townhouse with 2 concrete patios where the built-in planters were already full of shrubs and small trees. I grew food every year in an eclectic container mix varying from pots bought at a nursery, to wooden planters built from old shipping pallets, to some 24″ diameter ceramic pots found in a dumpster! Pots are very convenient as you can move them from time to time to bring plants into and out of the sun, and take them with you when you move. When I moved into that townhouse it was September and I brought a dozen tomato plants in 5 gal buckets with me from my old place. The neighbors immediately christened me the “mad gardener”! My movers thought I was nuts too…
You don’t need to confine your food plants to dedicated beds or containers. Mix them in with your ornamental plants: lettuce and parsley as edgings, eggplants and tomatoes as annual “shrubs”, grapes or kiwifruit as permanent vines, peas and beans as annual fence-and-trellis coverers.
If you do have some soil, but your space is small so whatever you do is going to be on display, then small raised beds are a good choice for you. The borders round the beds make them seem more “intentional” and decorative, and the extra depth means that you can improve on whatever soil you already have. More details below on building raised beds!
If you have more room, there are several ways to go.
One is the traditional vegetable garden with long rows of plants, often tilled each spring using a power tiller.
Another is to take your plot and split it into permanent beds about 3-4 ft wide, divided by paths, so that you never walk on the cultivated beds. This is currently a very popular way to lay out a vegetable garden, and it’s the way my own garden is designed. Permanent beds help with crop rotation (changing positions of plant families every year so that pests and diseases don’t build up) and allow you to build up really good soil in the beds – you apply all the good stuff only to the beds, not to the paths. Because of the good soil you can often plant closer and pack more plants into each bed. If the beds are raised, drainage will be better and the soil will warm faster in the spring.