How to Rotate Your Crops
Reduce pests and diseases and keep your edible garden thriving year after year with easy tips for rotating crops.
If you find yourself struggling with the same insect pests or diseases in your vegetable garden year after year, you probably need to start rotating your crops.
Most gardeners know that planting in the same spot over and over isn’t good for the soil. Tomatoes, corn, lettuce, and cabbage, among other crops, consume large amounts of nitrogen, while peas and beans are heavy feeders when it comes to phosphorus. Eventually the soil becomes less fertile as plants use up different kinds of nutrients.
But there’s another reason to practice crop rotation. If you don’t change your planting pattern, you can inadvertently invite pests and diseases to hang around. Many pests overwinter in the soil, and when they re-emerge, they dine on the same plants they enjoyed the year before. They’ll also attack other crops growing in the same spot that come from the same botanical family. Colorado potato beetles, for instance, will feast on the leaves of eggplants and tomatoes, which are all members of the nightshade family.
The same thing can happen with certain fungal and bacterial diseases. Common tomato diseases like Fusarium and Verticillium wilt are caused by fungal organisms that can persist in the soil for years, even if there’s no host plant around (a plant that they live on or with, in an interdependent relationship). These kinds of diseases can affect tomatoes and move on to other plants in the same family.
The solution, of course, is to move things around: to grow your crops in a different garden spot each year. That’s not always easy to do if you have a small garden, but it is possible.
You also need to be diligent about rotating your crops for a long period of time. Some experts recommend rotating tomatoes for as long as four to six years to help reduce the level of fungal organisms in the soil.
Try these “best-practice” ideas for rotating your crops, so you can enjoy a bountiful harvest of fruits and vegetables:
- Make a plan to rotate your crops, and don’t just depend on your memory. After you plant, sketch your garden or record where each crop was planted in a notebook or journal.
- List important dates on your map or in your journal. Record when you planted each crop and when you first noticed a pest or disease. This will help you know when to expect problems next year.
- Before you start rotating crops, do a soil test, or ask your county extension service office if they can test your soil. Tell them what you plan to grow, and add the amendments they recommend. If you can, do this in the fall, so the amendments have time to break down and blend with your native soil.
- Decide on an orderly way to rotate from one season to the next. An easy way to begin is by making a list of all the crops you want to grow. Then estimate how much room each crop will need in your garden. Melons, squash and tomatoes, for example, take a lot more space than beets, lettuce or carrots. Next, divide your crop into botanical families. For example, squash, cucumbers, watermelons and pumpkins are members of the cucurbita family, so put all of those crops in one group. Cabbages, kale, broccoli and other plants are members of the brassicaceae or cruciferae family, so they can go in another group. Keep sorting your crops until they're all separated. Then decide where to plant. You can start anywhere just make sure you don't put the same botanical group/family in the same spot for at least three years.
- Raised bed remedy. If you're planting in a raised garden bed of average size (small enough that you can reach into it from either side), you probably won't have enough room to rotate your crops. Instead, plan on removing and replacing your old planting soil or soil mix about every two years.
- Be aware that other factors can affect the success of your crop rotation, and don’t give up if you have an off year or two. A warm winter might contribute to a bigger insect population, or heavy rainfall might encourage disease.
- Put cover crops in your garden rotation. These “green manures” improve the soil by adding organic matter when they’re tilled under or worked in. Check with your local extension service office for recommendations on which ones to grow and when to plant in your region.
- Wait at least two to three years before planting the same crops in the same spot again. This gives insects and diseases time to die down.
Remember, even if you rotate, insects like potato leafhoppers can still move into your garden, and diseases can arrive on the wind or in soil that washes from one part of the garden to another. For best results, it’s also wise to plant disease-resistant varieties and clean up your garden at the end of each growing season. Destroy diseased plants, and remove soil and plant debris from stakes, trellises and other garden items. Rotating crops isn’t a cure-all, but it is a great idea that can help you grow a better garden.