Growing vegetables in the same location each year poses the risk of increased disease and insect damage and may deplete the soil of vital nutrients. Changing the layout of a large garden is relatively easy, but when it comes to raised beds, crop rotation may pose a bit of a challenge. Careful grouping of individual plants makes rotating crops easier to manage.
Group vegetables according to plant family and plant them in separate raised beds or sections of the bed. Rotate the entire contents of the bed to a new bed each year, if possible. Otherwise, move to a new section of the raised bed. A three- to four-year rotation, planting them in a new area each year for three to four years, is typically sufficient. After three to four years, it is safe to plant crops in their original beds.
Plant together vegetables from the nightshade family, such as tomatoes, peppers, potatoes and eggplant. These plants attract similar insects and are susceptible to many of the same diseases. Rotate the entire group to a new bed each year.
Grow legumes, such as beans, peas and lentils together in one bed. These crops are known as nitrogen-fixing plants and convert nitrogen in the air to usable nitrogen. These plants increase the amount of nitrogen in the soil, reducing the need for supplemental fertilizer in successive years. When rotated, they provide the new crop with a boost of nitrogen.
Group vegetables in the gourd family--such as cucumbers, melons, squash and pumpkin--in one bed. According to Sandra Mason, Unit Educator from the University of Illinois Extension Office, this includes cole crops such as cabbage, kale and broccoli. (ref 1) Not only does this make rotation easier, plants in the gourd family require similar care.
Plant together salad greens, such as lettuce, endive, chicory and artichoke. According to Roland E. Roberts, Extension Vegetable Specialist from the Texas Agricultural Extension Service, these vegetables make up the composite family and should be grown and rotated together.
Place onions, garlic, leek and chives together, rotating them to a new bed each year. These plants belong to the lily family.