The tomato (Solanum lycopersicum, synonym: Lycopersicon esculentum) is one of the most popular vegetables. They are easy to grow, cheap and healthy. Moreover, they can be used and processed in many different ways. They can be used in soups, sauces, salads and are delicious on bread. The tomato comes from the same family as chili peppers, potatoes, squash and tobacco. This family is called the nightshade family (Solanaceae).
Vegetable or fruit?
Botanically speaking, the tomato is actually a berry and is classified as a fruit. Most people call it a vegetable though, just as they do in horticulture.
The tomato has its origin in South America. Still, the tomato grows there in the wild. The Mayans and the Aztecs later, were the first people who cultivated the tomato. The Aztecs were the first to combine tomatoes with chili peppers and thus created the forerunner of salsas. How the Mayans and Aztecs in Central America gained access to the tomato is still a mystery, but probably birds ensured the spreading from South to Central America.
As with chillies the Spaniards spread tomatoes during their expeditions further across the world. The tomato was therefore introduced in the Caribbean, Asia and Europe in the 16th century.
The first description of the tomato comes from Italy in 1544. When the tomato was first introduced in Europe, most varieties were yellow. The Italians called the tomato therefore ‘pomo d'oro’, which means golden apple. To this day they call the tomato pomo d’oro.
The tomato was not immediately appreciated by everyone in Europe. Although the tomato was already introduced in the 16th century in the United Kingdom, it was not until the 18th century before the English people could appreciate this strange (and possibly toxic) vegetable and started to use it on a daily basis when preparing food. In their acceptance they were probably helped by the Southern European immigrants who entered the kingdom and who did appreciate the tomato.
The distribution to the United States came later from several sides, both from Europe and from the Caribbean islands. Also there the tomato is still as popular as ever.
The tomato plant
Although the tomato plant is perennial in the areas where they originate from, its being kept in Europe as an annual plant. Like chili peppers, tomatoes only grow in warm seasons. Once winter takes hold in Europe, the plant will die. The tomato plant is a crawling plant in fact, but usually we let the plant grow vertically. In our (wet) part of the world it is very easy for pests (snails, etc.) to attack the crawling plant and crawling on the ground puts them also at great risk of soil diseases.
The first tomato plants were indeterminate tomatoes. They grow in vines and produce tomatoes throughout the season. These plants can grow very large and only stop growing until the first frost occurs.
A major change in the tomato world came in 1914 when, by genetic mutation, a tomato plant was discovered which remained relatively small, had a shrub-like appearance and grew all its fruits in a short period: the determinate tomato. Choosing a tomato variety became much more easy for the tomato gardener with this new type of tomato. The indeterminate tomato and determinate tomato both have their advantages and disadvantages. More about that below.
The tomato is often a self-pollinating plant. That means that no other plant is needed to fertilize tomatoes. Wind and insects can take care of that. In greenhouses you can tap against the plant to help pollinating it.
After fertilization the fruit grows in about five weeks to its full extent. In the beginning slowly, later on faster. After this period the fruit starts to color.
Indeterminate versus determinate
The indeterminate tomato is the largest group of tomatoes and are usually pruned (see pruning and topping). The plant grows until it dies because of frost or disease. In warm countries the tomato plant can easily keep on growing. The growing season is longer there and the tomato plant is not always pruned.
In countries where the growing season is shorter, as in Northern Europe, we want the plant to maximize its energy on the growth and maturation of several trusses of tomatoes. This is achieved by pruning the plant and eventually top it.
Pruning a tomato plant is easy. In each leave axil a sideshoot (sometimes called sucker) is produced. We can remove the sideshoots with scissors or with the fingers, to ensure that there is only a main stem without side branches. If we don’t remove the sideshoots they will keep on growing and eventually produce flowers and tomatoes. This will cost the plant much energy, energy that’s better used in our climate for the growth and maturation of several trusses. These trussen will therefore grow larger and are ripe in time just before the plant dies of the first frost.
Often the tomato plant is topped after the fourth or fifth truss. The top is simply removed after the last two leaves above the last truss. One reason to stop the plant from growing is that it’s unlikely that future fruit in our climate will still ripen in August and September.
Indeterminate tomatoes are larger than determinate tomatoes and can grow meters high when they are not being topped. Indeterminate tomatoes should be supported with bamboo sticks or cages.
The determinate tomato (or bush tomato)
Determinate tomatoes stop growing themselves. Unlike indeterminate tomatoes which produce tomatoes throughout the season, determinate types produce tomatoes in a short period, all at once. Determinate tomato plants don’t need to be pruned, remain relatively small and have a shrub-like appearance. Many determinate tomatoes are perfect for growing in pots on a patio or balcony.
The determinate tomato is often smaller than the indeterminate tomato.
Hybrid or Heirloom tomato
By crossing tomato plants, plants can be obtained that combine the best features of both. Most tomatoes in the supermarkets are hybrid tomatoes, tomatoes that are limited in the number of shapes, colors and flavors. They are often less sensitive to diseases.
Nowadays it is getting more popular to grow your own tomatoes. With this popularity comes more interest in old tomato varieties that often taste deliciously. Some heirloom varieties are more than one hundred years old. These heirloom tomatoes have a great variety in form, color, taste and size. But they can be a bit more susceptible to disease.
Tomatoes can be divided in different ways.
Early tomatoes mature within 65 days after repotting.
Midseason tomatoes take between 65 and 80 days after repotting to mature and be ready for harvest.
Late tomatoes take between 80 and 100 days after repotting before they are mature.