Can You Plant Tomatoes Where Peppers Grew the Previous Year?

The Solanacaea Plant Family

• The nickname for the Solanacaea plant family is "the nightshades," evoking the deadliest of its family members. Genera in this family include tobacco (Nicotiana L.), peppers (Capsicum L.) and the solanums: eggplant (Solanum melongena), potatoes (Solanum tuberosa) and tomatoes (Solanum lycopersicum). As closely related family members, peppers and tomatoes have similar light and water requirements, nutritional needs and susceptibility to diseases.

Growing Conditions

• A reason for growing tomatoes and peppers in the same garden is their shared growing requirements. Both need full sun, well-drained soil and plenty of water. Although they can tolerate a variety of soil types, both tomatoes and peppers favor slightly acid, loamy soils rich in organic matter.

Nutritional Needs

• One important reason not to plant tomatoes in the same location as last year's peppers is depletion of necessary soil nutrients. Both vegetables, growing rapidly from seed to large fruit-bearing plants in a single season, are described as heavy feeders, using large amounts of nitrogen (N), phosphorus (P) and potassium (K) to create their delicious harvest. Both vegetables need similar ratios of nutrients, with an even balance of nitrogen, phosphorus and potassium, as found in a 5-5-5 NPK vegetable garden fertilizer. Heavy feeding also depletes soil of calcium, magnesium, iron and other nutrients. While some of the deficits can be addressed by soil testing and applying fertilizers, growing two crops with such similar nutritional needs in sequence challenges plant health and productivity.

Disease Vulnerability

• The most critical reason to avoid sequential plantings of tomatoes and peppers is diminishing damage by disease and pests. Tomatoes and peppers share several groups of diseases with each other and across their common family. Tobacco and cucumber mosaic viruses, soil-borne fungal infestations like fusarium and verticillium wilts, and insect-borne diseases like the tomato spotted wilt virus carried by thrips can severely damage both tomato and pepper plants. Plant debris from a previous year's crop can infect new plants. Some gardeners even keep tomato and other solanum plants out of their compost to diminish possible reinfection.

Small-Garden Rotation Strategies

• Making a sketch of your garden layout gives you more than memory to rely on when you plan next year's garden. Some gardeners use square-foot gardening techniques to prevent soil nutrient depletion and disease contamination. Knowing the families of the vegetables you want to plant can help you stage a rotation over two, three or even four years.