The tomato originated in the Andean Mountains of South America. The Inca people living in the area did not cultivate the tomato. The tomato traveled over 2,000 miles north of its center of origin to Central America where the pre-Mayan people first domesticated tomato plants. The Aztecs were the first people to cultivate, eat and name the tomato - tomatl or xtomatl. It was the wild, cherry size tomato Lycopersicon esculentum var cerasiforme, from which modern tomatoes are descended. The species is still found growing wild throughout the New World Tropics.

Cortez and his explorers are credited with finding the tomato in an Aztec market around 1520 and transporting the seed to Spain. In 1522 Italy was under Spanish rule and they introduced the tomato to Naples, Italy where it was cultivated.

The earliest written records of the tomato are in herbal books. Botanists placed the tomato in the nightshade family, which includes many poisonous plants. People thought tomatoes were poisonous also and the Herbal books said " this plant is more pleasant to the sight than either to the taste or smell because the fruit being eaten provoketh loathing and vomiting." Tomatoes were not eaten in England during the 1500 and 1600's because of the belief that they were poisonous.

Colonialists brought many plants from Europe back to the New World and the tomato was one of them. Thomas Jefferson raised them as an ornamental plant at Monticello in 1781. They were not being eaten.

It wasn't until the1830's that people in North America began to relish tomatoes as food. Colonel Robert Gibbon Johnson is credited for an event that changed opinions about tomatoes. In Salem, New Jersey in 1820 Colonel Johnson staged an event to eat a basketful of tomatoes at the local courthouse. An audience gathered to watch the colonel die. Colonel Johnson's physician warned that he would, "Foam and froth at the mouth...double over with appendicitis....if wolf peach is too ripe and warmed by the sun....exposing himself to brain fever." Colonel Johnson survived and slowly people began to accept the tomato as food. In 1835 tomatoes were regularly available in local markets in North America. The most popular uses were in preserves, pickles and catsup. Many cookbooks of the era highly recommended cooking tomatoes for at least three hours so that the "raw taste" would be lost.

In the 1880 James Vick's "Flower and Vegetable Catalog," Rochester, New York, there were 6 distinct types of tomatoes from seed offered to gardeners. A significant tomato breeding company in the 1880's was Livingston Seed Co. of Columbus, Ohio. This company bred 'Golden Queen' an early, large, smooth fruited, golden yellow tomato. W. Atlee Burpee listed 'Golden Queen' in their 1888 Farm Annual catalog. Burpee's catalog described 'Golden Queen' as "handsome yellow slices making a beautiful contrast in dish with the red tomatoes." Burpee listed twenty two tomato varieties for sale in 1888 with unusual names such as 'Acme,' 'Essex Early Hybrid,' and 'Nesbit's Victoria.'

A new development in the history of the tomato occurred in 1949 when W. Atlee Burpee introduced the first F1 Hybrid tomato, 'Big Boy.' Bred by Dr. Oved Shifriss 'Big Boy' offered gardeners earliness in a large, smooth red tomato. It was an instant success for both Dr. Shifriss and W. Atlee Burpee. Since 1949 thousands of hybrid tomatoes have been bred and introduced. The most significant breeding accomplishments have been the multiple disease tolerances bred into tomatoes. These tomatoes tolerate diseases such as fusarium wilt or root knot nematodes that would kill other tomato plants. Because of these tolerances there is less need for fungicides or pesticides to kill insects that spread diseases.

Nomenclature

The botanical name for tomato has changed several times. Its earliest name was Lycopersicon or literally, wolf peach. Once the tomato was placed in the Solanum (Solanaceae) family, the botanical name changed to Solanum lycopersicon. Today the tomato is known as Lycopersicon esculentum, literally edible wolf peach.

Classification

There are three ways to classify tomatoes. They are fruit shape, earliness to mature and color. Tomatoes are quite diverse and many gardeners enjoy growing several types. There are five major fruit shapes. From the smallest to the largest, they are cherry, plum, pear, standard and beefsteak. The National Garden Bureau found numerous cherry varieties available to gardeners. They are defined by weight in the range of 1/4 to one ounce. Cherry tomatoes are produced in clusters like grapes but have a tendency to crack if not picked regularly. The plum and pear tomatoes are the fruit shapes as described and weigh between 2 to 6 ounces. Normally they have meaty interiors, thick fruit walls and less gel than others. The standard tomatoes are round to globe shape weighing 4 to 8 ounces. The beefsteak size can be 2 pounds or more depending upon variety. The shape is usually oblate.

Tomatoes are categorized by their maturity date. The number of days to maturity means the number of days from planting outdoors to expected ripe fruit. Tomatoes can be early, mid-season or late. Early tomatoes will ripen from 55 to 65 days from transplanting. Mid-season is considered 66 to 80 days for ripe fruit. Late types require over 80 days to ripen. Tomatoes are colorful, ranging from creamy white through lime green to pink, yellow, golden, orange and red. The major differences among the colors are the flavors. Pink, yellow and orange are milder tasting than most red varieties. We have been led to believe that the yellow or orange tomatoes have less acid content but this is not necessarily true. People taste less acid in these colors. 

TOMATO CULTURE

Plant Growth

There are basically two types of plant growth for tomatoes. They are determinate and indeterminate. You can select the habit that is best for your garden use. Indeterminate growth means varieties grow, blossom. and produce tomatoes throughout the growing season until killed possibly by frost. The continuous growth produces many main stems all capable of flowering and producing fruit. Because of the abundant lush growth, pruning indeterminate plants is highly recommended. To support the plant growth and to keep tomatoes off garden soil, the National Garden Bureau recommends a stake for tomato plant support. Plants can be easily trained to the stake for vertical growth. The best combination of pruning and staking is to remove all but two growing stems and loosely tie the stems to the stake. To identify an indeterminate plant, look at the main stem. This can be identified by the growing tip at the top or end of the stem. In a normal plant, there are three leaf stems growing from the main stem. Above or below the three stems you will find a flower cluster. This pattern is repeated over and over on the main stem.

Indeterminate plants may be pruned to harvest larger tomatoes. Without pruning, plants produce smaller tomatoes but more of them. To prune, pinch out suckers. These are shoots that develop in the "U" between the main stem and a branch. Pinch out these shoots. This is best done by hand, pinching the shoots between fingers.

Determinate tomato plants are relatively compact and produce a full bushy plant. These plants will reach a predetermined height or number of fruit clusters and not grow beyond it. The plants flower, set fruit and ripen in a short time so that the main harvest is concentrated into a few weeks. This may be ideal for gardeners who wish to can or preserve the fresh tomato harvest. Instead of three leaf stems and a flower cluster, determinate varieties have two leaf stems and a cluster.

There is a third type called semi-determinate which is a bushy plant but will set and ripen fruit over a longer period of time than a normal determinate. The AAS Winner 'Celebrity' is a semi-determinate. The best way to grow determinate or semideterminate plants is to NOT prune and place a cage around the tomato while still quite small. The plant grows filling the cage. Gardeners need only pluck ripe fruit. It's as easy as growing a petunia from a bedding plant.

Sowing Seed

Many gardeners start their tomato plants from seed. This allows gardeners a wider choice of tomato varieties than if purchased as bedding plants. Tomato seed should be sown indoors 6 to 12 weeks before the last expected frost date. Most seed will germinate in 5 to 12 days. For maximum germination, the soil temperature needs to be warm, about 70 to 75 degrees F. Use a prepared, sterile germination mix as the growing media. Place this media in containers with holes for drainage. Water the media thoroughly and allow to drain. Sow seeds on the media and cover lightly with media or vermiculite. Mist the top of the media and cover with newspaper or plastic to prevent the media from drying out. Keep in a warm place and check every day for germination. When seeds have sprouted, remove the cover. Place in a sunny location, keep seedlings warm and water regularly. After a week or two transplant young plants into small 2 inch individual peat pots filled with a sterile soilless growing media. Dig out plants, carefully separate and disturb the roots as little as possible. Make hole in media, place plant into hole and push media next to plant to hold it upright. The plant can be planted deep, to the first leaf stem. Roots will develop along the buried main stem. Provide as much direct sunlight as possible. Up to twelve hours of light is desirable at this stage. Gardeners can use grow lights to supplement the natural sunlight. The plants may stretch or get leggy if they do not receive enough direct sunlight.

Preparing garden soil and hardening off

Garden soil needs to be prepared to grow transplants. Digging soil to add air pockets to the structure is advised for heavy clay soil. It is good to begin with a soil analysis to learn if any important nutrients are missing. Your local cooperative extension agency can assist you with information about a soil test. There are soil test kits available in stores too. Add compost and other organic materials to your soil to improve nutrients, texture and moisture holding capacity. Break large clods of soil into small pieces. Rake the garden bed so that it is flat and level.

It is recommended to harden off plants before placing them in the garden. The young plants are tender and need to be exposed gradually to the harsh outdoor climate. Put plants outside in a protected area where they will receive full sun, but out of the wind. Move plants inside at night. Continue this for 3 to 4 days. The day and night temperatures should be increasing but if it drops to 50 degrees, take the plants inside. After four days allow plants to be outside all day and night. After being outside for a week or two, the plants should be hardened off and ready to transplant.

Planting

Tomatoes are one of the easiest garden plants to grow. They need as much direct sunlight as possible to produce the highest yield. Wait until the air and soil have warmed before transplanting tomatoes. Native to the tropics, tomatoes require warm, 70 degrees F, temperatures for good growth.

There are several ways to plant a tomato. The traditional method is to dig a hole in the soil and place the plant in it. For northern gardeners, if your plants are tall and leggy, don't worry, just dig a deeper hole and bury the plant to the first leaf stem. The buried stem will grow roots and this helps develop a deep root system. This deep hole planting is not recommended for southern gardeners due to fungal rot attacking young stems. Some people use the trench method of planting. A long shallow hole is dug and the tomato plant laid horizontally into the trench. Pinch leaves off of the stem. Allow the top two to three inches of stem to lead out of the trench. Push soil on top of trench and push a pillow of soil under the top stem. The stem will grow up towards the sun. Because the bulk of the stem is buried at a shallow level, the newly developing roots and surrounding soil will warm up relatively quickly. This is a boon to gardeners living in a short growing season. With the roots close to the surface, be sure to water deeply to encourage deep root growth.

After planting, water. Continue watering lightly each day if it does not rain. After about 2 weeks of regular watering, plants should be established and you can decrease the watering. Throughout the growing season make mental notes about how long it has been since it rained. If it does not rain one week, be sure to water tomato plants as long as they are setting fruit. Established tomato plants need about one inch of precipitation per week from rain or irrigation.

Gardeners living in short growing seasons have garden supplies that can help protect plants from cold temperatures. A cloche or hot cap can be used to protect the newly transplanted tomatoes from freezing if night temperatures drop. Tomato plants will probably die if exposed to 32 degrees F without protection as they are not frost tolerant.

Plant Nutrition

Tomatoes need phosphorus, nitrogen, potash and minor elements. Many gardeners add a fertilizer to the soil. There are many types of fertilizer. Some are water soluble and can be used when watering tomatoes. There are granular forms to add to the soil before planting. The easiest to use is a time release fertilizer at the time of planting. No matter what kind of fertilizer is used always follow the directions on the label. Do not over fertilize because then you will have lush, tropical plants with little fruit set. Be sure to select a fertilizer that contains more phosphorus (P) than nitrogen(N) or potassium (K). Phosphorus promotes flowering and fruit set.

Container Culture

Gardeners living in urban environments can grow tomatoes in tubs or large patio containers. For best results select a determinate or compact bush plant habit for container culture. Cherry tomatoes can be grown in containers too. The container needs to be deep, at least a foot, with drainage holes on the bottom. Use a sterile growing media. Keep the plants evenly watered without overwatering. Allow the plants to receive as much direct sunlight as possible. Low light levels result in a leggy plant. They will still produce fruit, just fewer of them. Feed plants using a water soluble fertilizer. Apply as directed on the label but remember, nutrients tend to leach out of the pots faster than garden soil. Water often during hot weather possibly 3 or 4 times weekly as needed.

Harvest

To achieve the full tomato flavor, allow the fruit to fully ripen on the plant. Wait until it is deep red, or whatever final color the tomato is to be. Remember that once harvested, no additional sugars will go into the fruit. To harvest, gently hold the tomato and twist the tomato so that the stem separates from the vine. It is easy to damage the plant by pulling the entire fruit cluster off of the plant. Take the fruit one at a time unless you wish to remove the entire ripe cluster. Tomatoes are best stored at room temperature. It is absolutely unnecessary to place a ripe tomato in the refrigerator. Tomatoes will store on a kitchen counter for several days. At the end of the season when frost is predicted, all green tomatoes can be harvested and placed on a windowsill for future use. Most will gradually turn red and have some degree of tomato flavor. Placing unripe tomatoes in a closed paper bag will hasten the ripening process.

There are several long keeping tomatoes that can extend the fresh tomato season. These varieties were bred to retain the tomato flavor longer after harvest. All culture remains the same for growing these varieties.

Growing Problems

Most gardeners successfully grow tomatoes in their gardens without significant problems. The best approach is to be observant. Look at leaves regularly and notice any difference in leaf color, size or shape. Holes in leaves usually indicate there are insects eating leaves. If a problem develops, write down the problem, take a sample of the leaf or fruit and contact the local cooperative extension agent for assistance. The National Garden Bureau recommends rotating tomatoes and other crops in your garden. Do not grow the same crop in the same place year after year.

When browsing through the tomato section of seed packets in a store you may notice the letters V, F, N or TMV on the packet or in the description. These letters mean the plant is genetically tolerant of the following diseases or virus. Verticillium Wilt (V) is caused by a soilborne fungus. The symptoms of infection are wilting of older leaf tips, yellowing and browning of leaves in a V-shaped pattern and leaf drop beginning with the older foliage. As the fungus moves throughout the plant, all leaves curl upward and the stunted plant will not respond to water or fertilizer. Cool weather conditions encourage this disease which is common in soil. Fusarium Wilt (F) is also a soilborne fungal disease. This infection commonly occurs when the soil is above 75 degrees F. Light sandy soils are most susceptible to Fusarium, also soils with low Ph. Symptoms of this disease are yellowing, curving and dying leaves. Infected plants are stunted and fruits will be small or deformed. Nematodes (N) are microscopic worms living in the soil. Some nematodes are good, some bad. The bad ones are root knot nematodes and cause plants to wilt or portions of plants to dieback. To identify this problem, pull the tomato with roots from the soil. The roots will have growths or galls on them. This means the root knot nematodes are the problem. Tobacco Mosaic Virus (TMV) is one of the most widespread viruses affecting tomatoes. Weeds harbor the virus and insects feed on the weeds transmitting the virus to the plant. The virus source is tobacco. This virus turns leaves dark or light green, possibly even a mottled yellow appearance. It can also be caused by people who smoke cigarettes handling plants.

There is no cure for these four problems. If you suspect any of these problems may be infecting your plants, they should be destroyed. Do not place diseased plants into your compost. The easiest way to insure you do not have problems with these diseases is to grow tomatoes with disease or virus tolerances.

There are three fruit disorders that gardeners may encounter. They are blossom-end rot, cracking or catfacing, and sunscald. One of the most common fruit disorders is blossom-end rot. It begins with tan lesions on the blossom end of the tomato. The lesions enlarge and become dark sunken areas. It begins when fruit are about half developed. This rot appears during periods of high growth or when soil moisture is alternately high or low. Any soil condition that affects the plant's uptake of calcium can result in the rot. To help control this rot, try adding calcium soil amendments, water during dry weather and use a mulch to maintain more uniform soil moisture. Cracking usually occurs near the fruit stem while catfacing occurs near the blossom end. These are caused by environmental conditions such as fast growth caused by high temperatures and moisture levels, initial fruit growth during a dry spell followed by heavy rain or watering, or excessive swings in day and night temperatures. Some varieties such as AAS Winner 'Big Beef' are resistant to cracking and catfacing. Lastly, sunscald is the sun burning the tomato skin. It develops white, shiny, blisters on areas which are exposed to the sun. Normally leaf cover keeps the tomatoes in the shade. Sunscald can occur due to excessive pruning, insect damage to leaves or foliage disease causing leaf loss. There are no cures for these fruit disorders once they have damaged your tomatoes. Look for varieties that are more tolerant or resistant to these disorders and consider growing All America Selections Winners.

Nutritional Value

People have become more aware of the nutritional value of food in their diet. Eating healthy food and living a healthy life style have become important goals. Nutritionists suggest eating more fruits and vegetables for improved health. Tomatoes will provide abundant vitamins and minerals. A fresh, raw tomato contains an exceptional amount of Vitamin A. In addition, Vitamin C, potassium and calcium are available. A raw tomato contains a trace of sodium, whereas regular pack, canned tomatoes contain 100 times the amount of sodium. Americans and Canadians consume most of their lycopene from tomatoes and strawberries. Lycopene contributes to preventing certain types of cancers including prostate cancer. To offer the best, most nutritious food, grow your own tomatoes and eat them fresh from your garden. 

The National Garden Bureau acknowledges two tomato experts who read the fact sheet and contributed their knowledge. They are Julia Pruitt, Oklahoma State University, Oklahoma City, OK and Jim Waltrip, Seminis Vegetable Seeds, Saticoy, CA. Ball Horticultural Company generously donated the logo design. Photographs were taken by Steve Dibblee and Tom Eltzroth.

The 'Year of the Tomato' fact sheet is a service provided by the National Garden Bureau. The National Garden Bureau is a non profit organization and recognizes the seed company members who generously donate funds to publish these fact sheets.

More on tomato pests and diseases....