© 1996 Henrik Nordström

Crop rotation should be practiced by every vegetable gardener to prevent a buildup of disease organisms and insect populations specific to particular vegetables. A four-year rotation is usually recommended, which means that vegetables belonging to the same family should not be grown in the same spot of the garden more often than every four years. It is especially important to keep the carrot rust fly and cabbage maggot populations down and to alleviate the club root disease if already present in the soil. The tomato and potato blight is also avoided through crop rotation among other means.

Another often overlooked advantage of crop rotation is the optimum utilization of the soil's fertility without causing depletion of nutrients. A four-year rotation is also suitable for this purpose. In the fall before the first growing season, heavily fertilize the first year bed with fresh chicken manure or complete organic fertilizer. The next spring, plant heavy feeders like cabbage-family plants, corn, spinach, leeks and onions in this bed. The second year, do not fertilize at all and plant root crops like carrots, turnips, rutabagas and parsnips in this bed. These vegetables are not heavy feeders, and are able to utilize the residual fertilizer from the previous year. The third year, again do not fertilize, and plant legumes like peas and beans. These vegetables fix nitrogen from the air in their root nodules and release it into the soil. The fourth year, add large amounts of compost and plant potatoes. Potatoes produce some toxins which suppress weed growth. In the fall of the fourth year, fertilize heavily once more and also add lime, and start the cycle over. Having a succession of four equal-size areas of your garden ensures complete rotation. Perennial vegetables like asparagus, artichoke and rhubarb, as well as perennial herbs should be planted in a separate designated area and not undergo the four-year rotation.

The above system applies to garden soil of average fertility and texture. If your soil is very infertile or very sandy, you will have to apply some additional fertilizer in the interim years, and if your soil is more on the clayey side, you may have to lime every two or three years to release more tied-up nutrients.