How to Rotate Crops in Your Garden

Vegetable gardening takes a lot of nutrients out of soil, and certain kinds of plants can bring diseases and attract pests. For these reasons, you’ll want to rotate your crops to keep edibles at their best year after year. Rotating crops interrupts the life cycle of certain pests and diseases and allows the soil to replenish. This organic technique keeps the soil fertile and discourages plant disease and insect problems.

For example, tomatoes and corn are heavy feeders that deplete the soil of nitrogen and phosphorus. Planting tomatoes in the same place each year results in reduced crop yields and susceptibility to disease and pests. By moving tomato plants to different parts of the garden each year, the soil recovers more quickly.

While crop rotation is a principle of large-scale farming and gardening, the method is easy to incorporate in smaller home gardens. Begin on paper by grouping the vegetables in the garden according to family — root vegetables, legumes and fruiting plants (see following list). Each year, move the different families throughout the garden.

To make a crop rotation plan, draw the garden into blocks, then label each block according to family. Next year, move the families clockwise in the plan. Aim for at least three years, or preferably four, before returning a plant family to its original plot.

Tip: Before you plant, take time to test the soil with a soil test kit and adjust the balance of nutrients with soil amendments like compost. You can also get a low-cost soil test kit from your local Cooperative Extension Service.

Following are the plant families for home vegetable gardens. Grow these plants together in your garden and rotate the crops to different beds each year.

• Nightshade: tomato, pepper, eggplant, potato
• Carrot: celery, parsley, parsnip
• Goosefoot: beet, spinach, Swiss chard
• Gourd: cucumber, muskmelon, pumpkin, summer squash, watermelon, winter squash
• Grass: ornamental corn, popcorn, sweet corn
• Mustard: broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collard, kale, kohlrabi, mustard greens, radish, rutabaga, turnip
• Onion: chives, garlic, leek, onion
• Pea: bush bean, kidney bean, lima bean, pea, pole bean, soybean
• Sunflower: endive, lettuce, sunflower

At the end of each growing season, pull up and discard plant debris. Build up soil with organic compost and other amendments. When it's time to plant, you can rotate plantings clockwise or a system that works for you. It's a good idea to record your crop rotation plans in a garden journal for reference.

Sometimes, you may have a need to leave a block of the garden fallow, that is, without a crop. In this case, use a cover crop or green manure to improve the soil. Fallow land can become weedy or erode, but when you grow a green manure that is then turned under, you improve the soil structure and add nutrients back into the soil.

A cover crop is usually a legume because it takes nitrogen from the air and adds it into the soil. When you use a mix of legumes and non-legumes like a grass or grain, the soil gets the benefit of the nitrogen and decaying plant matter. Radish can be used as a cover crop, too. It has the advantage of breaking up compacted soil before dying back and creating humus. Look for varieties that are bred for use as cover crops.

Warm-season cover crop options are white Dutch clover, soybeans, cow peas, buckwheat and sorghum. Crimson clover, hairy vetch and rye are used in fall and winter.

Grown year after year, cover crops improve your garden soil. Cover crops are turned into the soil in the next season, preferably just after they flower so that the seeds are not set. Down the road, those seeds could become weeds.