Crop rotation is an important factor when planning the vegetable garden. Many disease organisms are soil-borne and may persist in the soil for several years. Disease problems often increase when the same crop is planted in the same area in successive years. Annually rotating your vegetables in the garden can help reduce the severity of diseases. Rotation may also help curb insect infestations. Insect populations and plant damage may increase when the same crop is planted in the same area over several years. Vegetable crops in the same botanical family are often susceptible to the same diseases and insects. For crop rotation to be effective, gardeners should not plant vegetables belonging to the same plant family in the same location for two or three years. Obviously, crop rotation in a small garden may be difficult. However, home gardeners should rotate their vegetable crops as best they can. To assist crop rotation efforts, the following list places the commonly grown vegetables in their proper botanical families. Alliaceae (Onion Family)

• Onion, garlic, leek, shallot, chive

Apiaceae (Carrot Family)

• Carrot, parsnip, parsley, celery

Asteraceae (Sunflower Family)

• Lettuce, endive, salsify, Jerusalem artichoke

Brassicaceae (Mustard Family)

• Cabbage, broccoli, cauliflower, Brussels sprouts, kohlrabi, turnip, radish, Chinese cabbage, kale, collards, rutabaga

Chenopodiaceae (Goosefoot Family)

• Beet, Swiss chard, spinach

Convolvulaceae (Bindweed Family)

• Sweet potato

Cucurbitaceae (Gourd Family)

• Cucumber, muskmelon, watermelon, squash, pumpkin, gourd

Fabaceae (Pea Family)

• Garden pea, snap bean, lima bean, soybean

Malvaceae (Mallow Family)

• Okra

Poaceae (Grass Family)

• Sweet corn, popcorn, ornamental corn

Solanaceae (Nightshade Family)

• Tomato, pepper, eggplant, potato, husk tomato

Accordingly, it would be inadvisable to plant potatoes where tomatoes were grown the previous year. Foliar blights are common diseases of tomatoes and potatoes and can severely damage both crops. Snap beans, cabbages, and cucumbers (any vegetable not in the Solanaceae family) would be better choices.

This article originally appeared in the March 27, 1998 issue, p. 28.