No home garden is complete without a few tomato plants. Home-grown tomatoes are far superior in taste and nutrition. Pick varieties labeled as determinate over indeterminate. Indeterminate varieties produce fruit over a longer period and tend to be larger and require more support. Determinates produce a large crop all at once, so they are usually smaller and more contained, thereby taking up less space. Varieties can trick you; cherry and grape tomato varieties may be small in fruit, but they are usually large, bushy plants. Plant Celebrity and Bush Early Girl for slicing tomatoes on plants that won't take over the garden. Allow 2 feet by 2 feet for each plant, space 2 feet apart. Tomatoes are best planted from seedlings, whether you start them indoors early or buy them from a nursery.
Sweet peppers stay fairly compact. Plant standard peppers such as Ace and California Wonder as they are good producers. Experiment with varieties that ripen in colors other than red. If you plant California Wonder, Sweet Orange Belle Hybrid II and Flavorburst Hybrid, you will have peppers in red, orange and yellow. Buy plants or start indoors in early spring.
Lettuce, spinach, kale, Swiss chard and other greens are not big space hogs, so incorporate varieties that do well in your climate. In the desert Southwest, these are winter vegetables; in cooler areas, plant in the summer. It is sometimes easier to sow these in a 3-foot-wide bed rather than in rows, so you can broadcast the seed instead of dealing with tiny seeds and lots of thinning. Leave paths on each side of the bed so you can weed and harvest.
Beets and carrots are good crops for a small garden since they don't take up a lot of room and you can eat the thinnings as well as the greens from the beet tops. These must be planted from seed as transplanting results in misshapen and malformed roots.
To expand your growing space, grow space eaters like pumpkins, cucumbers and melons by growing them on a fence or trellis. This will give you room in the rest of the garden for other plants. You will need to help them grow up, however, as they tend to want to stay on the ground.