Outside the tropics, tomatoes survive only as tender annuals. Every year new plants sprout from seeds collected or scattered in previous seasons. New tomato seedlings emerging where last year's fruit fell might make you think an old plant recovered, but tomato plants die when temperatures fall below freezing. Rare exceptions might include strains closely related to wild tomatoes, when grown in tropical or subtropical climates.
Tomatoes probably originated along the western coast of South America on the slopes of the Andes Mountains. Eight wild species still grow in Peru, and the natural range of wild tomatoes extends from Chile to Ecuador. Wild tomatoes might be found as far as 200 miles from the Pacific coast, but only grow as perennials where the plants never encounter freezing temperatures.
Today's domestic tomato varieties probably descend from a wild cherry tomato named Lycopersicon esculentum var. cerasiforme. Domestic cherry tomatoes bear fruit much larger than this original strain, but some modern cherry tomatoes retain the growth habits of wild perennials. Sweet 100 cherry tomato may grow vines 7 feet long in one growing season. Vigorous cherry tomato plants grown in warm climates could live longer than one year. Cherry tomatoes will not survive winter in colder growing zones.
The many varieties of cultivated tomatoes represent only 10 percent of the total species diversity, according to M. Abhary of the Middle East Regional Cooperation tomato breeding program. Tomato varieties selected for northern climates include determinate or bush types and indeterminate or vining types. The bush types typically grow quickly and then halt, producing a crop of fruit before losing vigor. Indeterminate types like Sweet 100 cherry tomato grow as long as temperatures favor the plant and continue to yield until frost.
Other factors such as plant disease also limit the lifespan of tomato plants. For the healthiest plants growers shouldn't plant tomatoes in the same spot in the garden two years running. Many fungal and viral diseases attack the plants and spores carry over in debris and soil. Crop rotation offers one of the best defenses against tomato diseases. Growing tomatoes as annuals supports that system and gives gardeners the best chance of a good harvest.
- Photo Credit Hemera Technologies/Photos.com/Getty Images
How to Plant Hanging Tomato Plants
Tomato plants don't only have to be planted in the ground. They can thrive hanging upside down as well. In fact, planting...