Solanum lycopersicum is an annual or perennial herbaceous vine native to Central and South America that produces a large, juicy, edible fruit known as tomato. Today there are over 10000 cultivated varieties. Although tomato is the world’s most popular vegetable, botanically it is a fruit.
I. Appearance and Characteristics
The tomato ( or ) is the edible berry of the plant Solanum lycopersicum, commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Nahuatl word tomatl gave rise to the Spanish word tomate, from which the English word tomato derives. Its domestication and use as a cultivated food may have originated with the indigenous peoples of Mexico. The Aztecs used tomatoes in their cooking at the time of the Spanish conquest of the Aztec Empire, and after the Spanish encountered the tomato for the first time after their contact with the Aztecs, they brought the plant to Europe, in a widespread transfer of plants known as the Columbian exchange. From there, the tomato was introduced to other parts of the European-colonized world during the 16th century.
Tomatoes are a significant source of umami flavor. They are consumed in diverse ways: raw or cooked, and in many dishes, sauces, salads, and drinks. While tomatoes are fruits—botanically classified as berries—they are commonly used culinarily as a vegetable ingredient or side dish.
Numerous varieties of the tomato plant are widely grown in temperate climates across the world, with greenhouses allowing for the production of tomatoes throughout all seasons of the year. Tomato plants typically grow to 1–3 meters (3–10 ft) in height. They are vines that have a weak stem that sprawls and typically needs support. Indeterminate tomato plants are perennials in their native habitat, but are cultivated as annuals. (Determinate, or bush, plants are annuals that stop growing at a certain height and produce a crop all at once.) The size of the tomato varies according to the cultivar, with a range of 1–10 cm (1⁄2–4 in) in width.
II. How to Grow and Care
Sunlight
Tomato plants require full sun, meaning six to eight hours of direct sunlight on most days. Indoors, the ideal spot is a bright, south-facing window.
Rotate the pots every day until the seedlings begin to flower and set fruit. Turning the pots so the other half of the plant faces out the next day will prevent the stems from becoming leggy and too flimsy to support fruit. In northern regions where winter days are short, you may need supplemental artificial light to grow tomatoes.
Artificial Light
If you don’t have a sunny window that provides bright light for at least six hours, install grow lights above the tomato plant containers. It helps to have a mechanism for raising and lowering the lights. This feature will prevent the plants from becoming too leggy by stretching toward the light. The ideal position for lighting is about 1 to 2 inches above the tops of the seedlings until they begin to flower and fruit.
Temperature and Humidity
One easy part about growing tomatoes indoors is they like average room temperatures, usually between 70 and 80 degrees Fahrenheit. Grow lights can help keep plants warm if your house generally falls below this threshold. Humidity typically isn’t an issue indoors.
Watering
The watering amount and frequency depend on the growth period of tomato. During sowing, the first watering should be thorough to promote seed germination. Soil humidity during seedling and blooming time should be moderate (about 65%). Water once a day, preferably in the morning or after five o’clock in the afternoon. Or you can water it when the soil is almost dry.
Soil humidity during germination and harvest should be high (at about 75%). Pay attention to soil humidity during harvest because it has a great impact on fruit quality. It is best to keep the soil in a moist state without accumulated water. Overwatering can easily cause the fruits to crack.
Soil
Tomato can adapt to all kinds of soil. The best soil is permeable, well-drained loam or sandy loam, which is rich in organic matter and neutral or slightly acidic. The optimum soil pH is 6.0-6.5. Before sowing, add organic fertilizer and calcium fertilizer to the soil.
If planted in a flowerpot, the recommended proportions of culture medium are garden soil : peat : mushroom compost : vermiculite = 1:1:1:1, and the medium should be combined with manure or a compound fertilizer of potassium sulfate.
Fertilizing
Soil fertility greatly affects the quantity and quality of your harvest. Apply sufficient fertilizer during planting to ensure growth; usually, a compound fertilizer with some calcium superphosphate is advisable. Apply fertilizer again in the later stage of growth so tomato gets sufficient nutrients.
Within a week after transplant, a small amount of urea can be applied. Later, after the first fruits are harvested, the plant needs more nutrients to promote the growth of subsequent fruits, so add NPK compound fertilizer. The fertilizer amount and times should be adjusted according to the varieties and growth conditions to realize a high yield.
Planting Instructions
If you are planting tomato from seed, you can choose your timing according to the climate conditions. Generally speaking, sow the seeds in the spring. Soak seeds in hot water before planting to promote germinating.
Transplant seedlings from spring through fall when 4-5 leaves grow out. Make sure to transplant after the last frost in spring, and before the temperature drop below 10 ℃ in fall. If you plant commercial seedlings, you can start on this step.
To prepare the soil, turn it over, sterilize it with fungicide, and add in decomposed fertilizer. Spacing is determined according to the characteristics of the variety; usually at or above 40 cm. Water thoroughly after planting and keep the soil moist as much as possible.
Most varieties fall into two types: determinate and indeterminate. It’s important to know which type suits your garden best. Determinate varieties grow to a certain height and flower, set fruit, and ripen at the same pace. Indeterminate varieties grow, set fruit, and ripen continuously until killed by frost.
Determinate varieties can grow well in limited spaces, or even in containers or flower pots, and can be harvested in a short time, so they are suitable for gardens in colder areas. If you have plenty of space and are willing to let them grow continuously, try indeterminate varieties. You can continuously harvest fruit for two or three months on these varieties.
Pruning
When pruning, leave one stem or two branches (besides the main branch, the strongest lateral branch should be left). The other lateral buds, branches, and old yellow leaves at the lower parts can be completely pruned. Don’t prune on rainy days, because the air is humid and plants could get infected. If stems have too many tomatoes, remove some weak ones to ensure sufficient nutrients for remaining fruits. Leave 4-5 large fruits on each stem.
Potting and Repotting
When planting purchased seedlings, place them in the pot just slightly deeper than they were in the seedling container so that a portion of the stem is buried.
Once established, tomato plants don’t like their roots disturbed. So, rather than repotting as the plant grows, select a container large enough to accommodate your plant’s mature size.
Pollination
Tomatoes are self-pollinating, meaning they don’t need insects for pollination. But they will need hand pollinating when grown indoors or an oscillating fan to mimic wind conditions that would normally spread pollen between blooms.
To hand pollinate, gently shake the stems every day or so when the plants bloom or touch each blossom with a cotton swab to move pollen from one bloom to the next.
III. Uses and Benefits
- Ornamental uses
- Medicinal uses
- Culinary uses
Though it is botanically a berry, a subset of fruit, the tomato is considered a vegetable for culinary purposes. It has a strong savoury umami flavour, rather than significant sweetness (see above). Chef Heston Blumenthal observed that the inner pulp had more flavour that the flesh; a subsequent academic study in which he participated confirmed that the pulp had up to eleven times more glutamic acid, which carries umami flavour, than the flesh.
Although tomatoes originated in the Americas, the tomato is now grown and eaten around the world. It is used in diverse ways, including raw in salads or in slices, stewed, incorporated into a wide variety of dishes, or 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 have become extensively used in Mediterranean cuisine as a key ingredient in pizza and many pasta sauces. Tomatoes are also used in Spanish and Catalan dishes, such as gazpacho and pa amb tomàquet.
- Other uses
The potato tuber moth (Phthorimaea operculella) is an oligophagous insect that prefers to feed on plants of the family Solanaceae such as tomato plants. Female P. operculella use the leaves to lay their eggs and the hatched larvae will eat away at the mesophyll of the leaf.
Tomato forms a mutually beneficial symbiosis with arbuscular mycorrhizal fungi such as Rhizophagus irregularis. Scientists use tomatoes as a model species for investigating this symbiosis.
IV. Harvesting and Storage
- Harvesting
When the color of the fruits changes from green to red, they can be harvested. Determinate tomatoes can be harvested once, while indeterminate tomatoes bear continuously. Tomato is prone to crack in heavy rain, so harvest before the rains.
- Storage
Tomatoes keep best unwashed at room temperature and out of direct sunlight. It is not recommended to refrigerate them as they take a mealy texture and lose flavour.
Storing the stem down can prolong shelf life, as it may keep from rotting too quickly.
Unripe tomatoes can be kept in a paper bag to ripen.
Tomatoes are easy to preserve whole, chopped, or as tomato sauce or concentrated paste by home canning. The fruit can also be preserved by drying, sometimes in the sun where climate permits, and sold either in bags or in jars with oil.