Crop rotation is one of the most effective tools for managing pests and maintaining soil fertility, but there aren't many specific recommendations for how to go about it. A common approach on vegetable farms is to rotate crops by families. Another strategy is to alternate vegetable crops with field or forage crops, such as small grains or alfalfa. Some growers try to rotate fields so they are in cash crops one year and cover crops the next year. On farms with limited land for rotation, sweet corn is a good rotation crop since it hosts very few insects or diseases that affect other vegetables.

Too many growers rotate their crops using the seat of their pants technique, relying on memory and making decisions day by day when planting. To make the most of crop rotation you need detailed records of where crops were grown in the past as well as a written plan for how crops will be arranged in the future. Start by making a map of your farm and other fields you may use including those that are rented. Label the fields or sub-fields with names and acreage. Make photocopies of the map and at the end of each season fill one in and date it, noting any serious pest or soil problems in a field. Prior to the growing season, fill in a new map with your best guess as to where crops will go, depending on growing conditions and other factors. Try to develop a plan that results in the most years possible between planting similar crops in a given location.

As you plan, remember that rotation helps prevent some pests but not others. For insects that over-winter near the crop they infested, such as Colorado potato beetle, European corn borer, or flea beetle, it helps to plant host crops as far away as possible the next year. Having a barrier such as a road or river between last year's crop and this year's can enhance the rotation effect. Rotation will not help prevent insect damage from pests that migrate into the area, such as potato leafhopper or corn earworm.

For diseases that are soil-borne or over-winter in crop residues, rotating out of susceptible crops is a key to preventing infection, as in the case of Phytophthora blight, early blight, and many other diseases. However, host crops must be rotated far enough away to avoid infection through blowing or washing soil. The movement of soil on equipment from field to field can introduce diseases and weeds into a new field. A few minutes cleaning equipment before moving to a another field can help avoid serious pest problems. For some diseases, such as club root of crucifers, susceptible weeds must be controlled if rotation is to be effective. As with insects, rotation cannot prevent airborne diseases that move in from other areas, such as downy mildew, nor can it prevent seed-borne or insect-carried diseases.

Rotating crops is also good for soil health because it leads to changes in tillage, rooting depth and nutrient removal. Some crops increase beneficial microbial activity. Rotation plans should include time for growing soil-improving crops, a practice that is critical to sustaining production. If possible, always include winter cover crops in your rotation plans and try to use summer cover crops or year-long green manures to 'rest' fields from time to time. For a description of different cover crops suitable for our area see the cover crop section.