Identify the other members of the "nightshade" vegetable family in which tomatoes and peppers belong. In the home vegetable garden, they also include eggplants and potatoes.
Avoid planting any of members of the nightshade family in the same location as the previous three years, even if they're different plants. For example, never plant tomatoes where peppers, eggplants and potatoes were planted in the last three years. This is the basic rule for planting tomatoes and peppers; however, there are more complex things to consider when rotating these plants, if desired, to grow a more successful and fruitful garden.
Classify the other vegetables in your garden into their respective families. According to Texas Agricultural Extension Service, some of the most common vegetables in their respective families are: the mustard family that includes radishes, cabbage, turnips, broccoli and cauliflowers; the grass family that includes corn; the legume (or pea) family that includes all peas and beans; the goosefoot family that includes spinach, beets and chard; the gourd family that includes squash, pumpkin, watermelon and cucumbers; the parsley family that includes carrots, celery and parsley; the composite family includes lettuce and artichokes; the lily family that includes onions, garlic and leeks; and the mallow family that includes okra.
Learn which plants are good to plant just before and after tomatoes and peppers. For example, corn, according to Clemson University Extension, is an excellent crop to grow the year before tomatoes because the organic matter they produce is resistant to tomato (and pepper) diseases. In addition, plant shallow rooted plants, such as lettuce and beets after deep-rooted plants, such as peppers and tomatoes, which discourage weed growth.
Plan out your garden into a four-year rotation cycle. On paper, draw a rough sketch of your garden and divide it into sections and decide where you are going to plant each family in the next four years. For example, in one section of your garden, in year one, plant corn (grass family). In year two, plant members of the nightshade family (which are peppers and tomatoes). In year three, plant lettuce and other members of the composite family. In year four, plant members of the mustard family, such as broccoli and turnips. Then, repeat this cycle every four years.