Solanum lycopersicum

From The Plant Encyclopedia

Tomato, Garden Tomato, Tomato Plant, Tomatoes

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Solanum lycopersicum

Kingdom Plantae
Order Solanales
Family Solanaceae
Genus Solanum
Varieties in this species
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Aden Earth Zone

4 - 20


  • Cultivation: Easy-To-Grow, For-Gardeners
  • Light: Sun
  • Soil: Rich, Loam
  • pH: 7
  • Moisture: Medium, Well-Drained


  • Form: Shrub, Vine, Herbaceous
  • Habit: Annual
  • Flower: Small, White
  • Fruit/Seed: Large, Green, Yellow, Orange, Red, Purple
  • Foliage: Leaves, Green
  • Uses: Edible, Industrial


The tomato is a savory, typically red, edible Fruit, as well as the plant (Solanum lycopersicum) which bears it. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in Greenhouses in cooler climates. The tomato fruit is consumed in diverse ways, including raw, as an ingredient in many dishes and sauces, and in drinks. While it is botanically a Fruit, it is considered a Vegetable for culinary purposes (as well as by the United States Supreme Court, see Nix v. Hedden), which has caused some confusion. The fruit is rich in Lycopene, which may have beneficial health effects. The tomato belongs to the nightshade family. The plants typically grow to in height and have a weak stem that often sprawls over the ground and vines over other plants. It is a perennial in its native habitat, although often grown outdoors in temperate climates as an annual.


The tomato is now grown worldwide for its edible Fruits, with thousands of Cultivars having been selected with varying fruit types, and for optimum growth in differing growing conditions. Cultivated tomatoes vary in size from tomberries, about 5mm in diameter, through Cherry tomatoes, about the same size as the wild tomato, up to beefsteak tomatoes or more in diameter. The most widely grown commercial tomatoes tend to be in the diameter range. Most cultivars produce red fruit; but a number of cultivars with yellow, orange, pink, purple, green, black, or white fruit are also available. Multicolored and striped fruit can also be quite striking. Tomatoes grown for Canning and sauces are often elongated, long and diameter; they are known as Plum tomatoes, and have a lower water content. Roma-type tomatoes are important cultivars in the Sacramento Valley.

Quite a few seed merchants and banks provide a large selection of heirloom seeds. Tomato seeds are occasionally organically produced as well, but only a small percentage of organic crop area is grown with organic seed . The definition of an heirloom tomato is vague, but unlike commercial hybrids, all are self-pollinators who have bred true for 40 years or more.

Tomatoes are warm-season, frost susceptible plants that need a growing season of at least three months, so they’ll grow in all climate zones of Australia. In warm, frost-free regions, tomatoes can be grown throughout the year; in temperate and cooler climes, the best time to plant is from the end of winter right through spring. However, to give tomatoes in cooler climates a head start in life, the seeds can be germinated in small pots under glass, or in a mini propagator. Simply sow your seeds six to eight weeks before you intend to plant them out, and keep them in a warm, sunny spot. When plants have at least three leaves, they can go in the ground. '

Choose an open position that receives at least six hours of full sun each day and is protected from strong winds. Tomatoes grow well with 7 hours of sunlight a day. A fertilizer with an NPK ratio of 5-10-10 is often sold as tomato fertilizer or vegetable fertilizer, although manure and compost are also used.

Tomatoes can thrive in either light or heavy soils, as long as they’re well drained and enriched with organic matter. Before you plant them out, prepare the soil by digging in well-rotted compost and a tomato-specific fertiliser, such as Osmocote Plus Organics Vegetable, Tomato & Herb. To encourage flowers and fruit rather than leafy growth, avoid adding too much animal manure. And, to help prevent disease build-up in the soil, don’t plant your tomatoes in the same spot two years running. As for pots, use a top-quality potting mix.

Most tomatoes require staking, as they have a natural trailing or climbing habit. But there are certain compact varieties, such as ‘Tiny Tim’, that don’t need to be staked, so check when you’re buying. If you train the plant upwards, it will take up less space and you’ll save the fruit from the damage of coming into contact with damp soil. Use stakes that are 1.5-2m long and hammer them into the ground near the plant’s base, about 5cm from the stem. As the plant grows, tie it to the stake using soft cloth or twine. How to water your tomatoes
Give your tomatoes regular water after planting, then water weekly while they’re still small. When the plants are carrying a heavy crop or the weather is hot and dry, increase this to twice a week. To help avoid fungal problems, avoid getting the leaves wet when you’re watering the soil. 

With fertiliser dug in during soil preparation, you won’t need to add any more until the plants start to flower. A soluble fertiliser high in potassium, such as Yates Thrive Concentrate Flower & Fruit Liquid Plant Food, is a good choice. Or, you could use one that’s been specially formulated for tomatoes (for example Yates Thrive Concentrate Tomato Food). Apply it when the flowers first appear, then weekly through the growing season. 

To suppress weeds and help conserve moisture in the soil, apply a good layer of mulch. Lucerne, sugarcane or pea-straw mulch are all good options – just make sure you keep it away from the stem to discourage stem rot.

To enjoy the best-tasting fruit possible, it’s best to pick your tomatoes when they’re red-ripe. If they are left to overripen, they will become floury and lose their sweetness.


There are many (around 7500) tomato varieties grown for various purposes.

Heirloom tomatoes are becoming increasingly popular, particularly among home gardeners and organic producers, since they tend to produce more interesting and flavorful crops at the cost of disease resistance and productivity. Hybrid plants remain common, since they tend to be heavier producers and sometimes combine unusual characteristics of heirloom tomatoes with the ruggedness of conventional commercial tomatoes. 

Tomato Broad Categories: ==

  • '"Slicing" or "globe"' tomatoes are the usual tomatoes of commerce, used for a wide variety of processing and fresh eating.  
  • 'Beefsteak' tomatoes are large tomatoes often used for sandwiches and similar applications. Their kidney-bean shape, thinner skin, and shorter shelf life makes commercial use impractical.  
  • 'Oxheart ' tomatoes can range in size up to beefsteaks, and are shaped like large strawberries. *
  • Plum' tomatoes, or paste tomatoes (including pear tomatoes), are bred with a higher solid content for use in Tomato sauce and paste and are usually oblong.
  • 'Pear ' tomatoes are obviously pear shaped and based upon the San Marzano types for a richer gourmet paste. *
  • Cherry ' tomatoes are small and round, often sweet tomatoes generally eaten whole in salads.  
  • 'Grape' tomatoes, a more recent introduction, are smaller and oblong, a variation on plum tomatoes, and used in salads.  
  • 'Campari' tomatoes are also sweet and noted for their juiciness, low acidity, and lack of mealiness. They are bigger than cherry tomatoes, but are smaller than plum tomatoes.

Diseases and pests

Tomato cultivars vary widely in their resistance to disease. Modern hybrids focus on improving disease resistance over the Heirloom plants. One common tomato disease is Tobacco mosaic virus, and for this reason smoking or use of Tobacco products are discouraged around tomatoes, although there is some scientific debate over whether the virus could possibly survive being burned and converted into smoke. Various forms of Mildew and Blight are also common tomato afflictions, which is why tomato cultivars are often marked with a combination of letters which refer to specific disease resistance. The most common letters are: V – Verticillium wilt, F – Fusarium wilt strain I, FF – fusarium wilt strain I & II, N – Nematodes, T – Tobacco mosaic virus, and A – Alternaria.

Another particularly dreaded disease is Curly top, carried by the Beet leafhopper, which interrupts the lifecycle, ruining a nightshade plant as a crop. As the name implies, it has the symptom of making the top leaves of the plant wrinkle up and grow abnormally.

Some common tomato pests are Stink bugs, Cutworms, Tomato hornworms and Tobacco hornworms, Aphids, Cabbage loopers, whiteflies, Tomato fruitworms, Flea beetles, Red spider mite, Slugs, and Colorado potato beetles.

When insects attack tomato plants, they produce the Plant peptide hormone, Systemin, which activates defensive mechanisms, such as the production of protease inhibitors to slow the growth of insects. The hormone was first identified in tomatoes, but similar proteins have been identified in other species since.


In the wild, original state, tomatoes required cross-Pollination; they were much more self-incompatible than domestic cultivars. As a floral device to reduce selfing, the Pistil of wild tomatoes extends farther out of the flower than today's cultivars. The Stamens were, and remain, entirely within the closed corolla.

As tomatoes were moved from their native areas, their traditional Pollinators, (probably a species of halictid Bee) did not move with them. The trait of self-fertility became an advantage, and domestic Cultivars of tomato have been selected to maximize this trait.

This is not the same as Self-pollination, despite the common claim that tomatoes do so. That tomatoes pollinate themselves poorly without outside aid is clearly shown in Greenhouse situations where pollination must be aided by artificial wind, vibration of the plants (one brand of vibrator is a wand called an "electric bee" that is used manually), or more often today, by cultured Bumblebees. The Anther of a tomato flower is shaped like a hollow tube, with the Pollen produced within the structure, rather than on the surface as in most species. The pollen moves through pores in the anther, but very little pollen is shed without some kind of outside motion. The best source of outside motion is a sonicating bee such as a bumblebee or the original wild halictid pollinator. In an outside setting, wind or animals provide sufficient motion to produce commercially viable crops.

Hydroponic and greenhouse cultivation

Tomatoes are often grown in Greenhouses in cooler climates, and there are cultivars such as the British 'Moneymaker' and a number of cultivars grown in Siberia that are specifically bred for indoor growing. In more temperate climates, it is not uncommon to start seeds in greenhouses during the late winter for future transplant.

Hydroponic tomatoes are also available, and the technique is often used in hostile growing environments as well as high-density plantings. 

Picking and ripening

Tomatoes are often picked unripe (and thus colored green) and ripened in storage with Ethylene. Unripe tomatoes are firm. As they ripen they soften until reaching the ripe state where they are red or orange in color and slightly soft to the touch. Ethylene is a hydrocarbon gas produced by many fruits that acts as the molecular cue to begin the ripening process. Tomatoes ripened in this way tend to keep longer but have poorer flavor and a mealier, starchier texture than tomatoes ripened on the plant. They may be recognized by their color, which is more pink or orange than the other ripe tomatoes' deep red, depending on variety.

A machine-harvestable variety of tomato (the "square tomato") was developed in the 1950s by University of California, Davis's Gordie C. Hanna, which in combination with the development of a suitable harvester revolutionized the tomato-growing industry. In 1994 Calgene introduced a genetically modified tomato called the 'FlavrSavr' which could be vine ripened without compromising Shelf life. However, the product was not commercially successful (see main article for details) and was only sold until 1997.

Recently, stores have begun selling "tomatoes on the vine", which are determinate varieties that are ripened or harvested with the fruits still connected to a piece of vine. These tend to have more flavor than artificially ripened tomatoes (at a price premium), but still may not be the equal of local garden produce.

Slow-ripening cultivars of tomato have been developed by crossing a non-ripening cultivar with ordinary tomato cultivars. Cultivars were selected whose fruits have a long shelf life and at least reasonable flavor.

At home, fully ripe tomatoes can be stored in the Refrigerator, but are best kept at Room temperature. Tomatoes stored in the refrigerator will still be edible but tend to lose flavor; thus the "Never Refrigerate" stickers sometimes placed on tomatoes in supermarkets.


The tomato is now grown and eaten around the world. It is used in diverse ways, including raw in Salads, and processed into Ketchup or Tomato soup. Unripe green tomatoes can also be breaded and fried, used to make salsa, or pickled. Tomato juice is sold as a Drink, and is used in cocktails such as the Bloody Mary.

Tomatoes are Acidic, making them especially easy to preserve in home Canning whole, in pieces, as Tomato sauce or paste. The fruit is also preserved by drying, often in the sun, and sold either in bags or in jars with oil.

Tomatoes are used extensively in Mediterranean cuisine, especially Italian and Middle Eastern cuisines. They are a key ingredient in Pizza, and are commonly used in Pasta sauces. They are also used in Gazpacho (Spanish cuisine) and Pa amb tomàquet (Catalan cuisine).

Though it is botanically a Berry, a subset of Fruit, the tomato is a Vegetable for culinary purposes, because of its savory flavor (see below).

Medicinal properties

Lycopene, a carotenoid antioxidant, has been shown to protect against oxidative damage in many epidemiological and experimental studies. In addition to its antioxidant activity, other metabolic effects of lycopene have also been demonstrated. The richest source of lycopene in the dietis tomato and tomato derived products. Tomato consumption has been associated with decreased risk of breast cancer, head and neck cancers and might be strongly protective against neurodegenerative diseases. Tomatoes and tomato sauces and puree are said to help Lower urinary tract symptoms (BPH) and may have anti-cancer properties.


Tomatoes that are notyet ripe are optimally stored at room temperature uncovered, out of direct sunlight, until ripe. In this environment, they have a shelf life of 3 to 4 days. When ripe, they should be used 1 to 2 days. Tomatoes should only be refrigerated when well ripened, but this will affect flavor. = Breeding = Active breeding programs are ongoing by individuals, universities, corporations, and organizations. The Tomato Genetic Resource Center, Germplasm Resources Information Network (GRIN), AVRDC, and numerous seed banks around the world store seed representing genetic variations of value to modern agriculture. These seed stocks are available for legitimate breeding and research efforts. While individual breeding efforts can produce useful results, the bulk of tomato breeding work is at universities and major agriculture related corporations. These efforts have resulted in significant regionally adapted breeding lines and hybrids such as the Mountain series from North Carolina. Corporations including Heinz, Monsanto, BHNSeed, Bejoseed, etc., have breeding programs that attempt to improve production, size, shape, color, flavor, disease tolerance, pest tolerance, nutritional value, and numerous other traits.

Fruit or vegetable?

Botanically, a tomato is a Fruit: the ovary, together with its seeds, of a Flowering plant. However, the tomato has a much lower sugar content than other fruits, and is therefore not as sweet. Typically served as part of a salad or Main course of a meal, rather than at Dessert, it is considered a Vegetable for most culinary purposes. One exception is that tomatoes are treated as a fruit in home canning practices: they are acidic enough to be processed in a water bath rather than a pressure cooker as "vegetables" require. Tomatoes are not the only foodstuff with this ambiguity: Eggplants, Cucumbers, and squashes of all kinds (such as Zucchini and Pumpkins) are all botanically fruits, yet cooked as vegetables.

This argument has had legal implications in the United States. In 1887, U.S. Tariff laws that imposed a duty on vegetables but not on fruits caused the tomato's status to become a matter of legal importance. The U.S. Supreme Court settled the controversy on May 10, 1893 by declaring that the tomato is a vegetable, based on the popular definition that classifies vegetables by use, that they are generally served with dinner and not dessert (Nix v. Hedden (149 U.S. 304)). The holding of the case applies only to the interpretation of the Tariff Act of March 3, 1883, and the court did not purport to reclassify the tomato for botanical or other purpose.

Tomatoes have been designated the state vegetable of New Jersey. Arkansas took both sides by declaring the "South Arkansas Vine Ripe Pink Tomato" to be both the state fruit and the state vegetable in the same law, citing both its culinary and botanical classifications. In 2009, the state of Ohio passed a law making the tomato the state's official fruit. Tomato juice has been the official beverage of Ohio since 1965. A.W. Livingston, of Reynoldsburg, Ohio, played a large part in popularizing the tomato in the late 19th century, his efforts are commemorated in Reynoldsburg with an annual Tomato Festival.

In 2001 the Council of the European Union in a directive stated that tomatoes should be considered fruits.