Rotating your vegetables according to family prevents soil-bourne pests and diseases from building up in the soil. Rotating where you grow your vegetables can also help to restore soil nutrients.
Ideally, try not to plant crops from the same family in the same spot for at least 3 years. See the chart for details. Try to follow heavy feeding crops like corn with a nitrogen-fixing crop like peas or beans to restore nitrogen.
Keep a garden journal of where you plant your vegetables so you remember year to year.
Every vegetable garden is unique. Many gardeners grow the same selection of vegetables from year to year. Divide your vegetable garden into manageable sections or beds and make a plan. Place vegetable crops from the same family in each section and every year shift where you grow crops.
If you forget to write it down, take a picture of your garden at the end of summer so that you remember where you planted things next spring!