Everything you need to know about successfully growing tomatoes – one of the most commonly grown and most loved vegetables.
The tomato originated in the Andean Mountains of South America, but the Inca people living in the area did not cultivate it. It 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 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 one herbal 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.” As a result, tomatoes were not eaten in England during the 1500s and 1600s.
It wasn’t until the 1830s 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 him die. His 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.
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.
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. There are 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 two to six ounces. Normally they have meaty interiors, thick fruit walls and less gel than others. The standard tomatoes are round to globe shape weighing four to eight ounces. The beefsteak size can be two 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. So if you are growing tomatoes in an area with a short growing season, choose wisely.
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.
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, stakes are recommended for 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. 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 between your 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 best way to grow determinate or semi-determinate 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.
Many gardeners start growing tomatoes from seed. Sow the seeds 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 deeply, to the first leaf stem. Roots will develop along the buried main stem. Provide as much direct sunlight as possible. Up to 12 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 to Plant
Digging soil to add air pockets to the structure is advised for heavy clay soil. Do a soil analysis to learn if any important nutrients are missing. 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 your growing tomatoes before placing the plants 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 are out of the wind. Move plants inside at night. Continue this for three to four days. The day and night temperatures should be increasing but if it drops to 50 degrees F, take them 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.
Growing tomatoes is one of the easiest gardening jobs. They need as much direct sunlight as possible to produce the highest yield. Wait until the air and soil have warmed before transplanting. 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 the 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 two weeks of regular watering, plants should be established and you can decrease the watering. Throughout the growing season water weekly if it does not rain. Established tomato plants need about one inch of precipitation per week from rain or irrigation.
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.
Tomatoes need phosphorus, nitrogen, potash, and minor elements. Many gardeners add a fertilizer or rich compost to the soil. The easiest commercial fertilizer to use is a time release fertilizer at the time of planting. 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.
Gardeners living in urban environments can be successful at growing 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. Water often during hot weather.
To achieve the full tomato flavor, allow the fruit to fully ripen on the plant. To harvest, gently hold the tomato and twist 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. At the end of the season when frost is predicted, all green tomatoes can be harvested and placed on a windowsill. 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.
Most gardeners are successful at growing 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. It is best to rotate 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 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 growing tomatoes.
Tomatoes will provide your diet with 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. For the best, most nutritious food, growing tomatoes and eating them fresh from your garden cannot be beat.