Tomatoes are an annual plant that must begin anew from seed each year. With hundreds of varieties, tomatoes come in many shapes, sizes, colors and with multiple uses. In spite of their vast differences, they share the same life cycle from seed to plant to fruit setting. While the time it takes to complete the cycle may vary from one tomato species to another, the process itself does not change.
The seeds of tomatoes like any other angiosperm are contained within the fruit, the tomato itself. Whether the tomato is left to ripen and then decompose naturally, releasing its seeds to the soil or the seeds are harvested and stored for future planting, all new tomato plants begins as tiny seeds. Within the tomato they are suspended in a gel that protects them. Outside the tomato, they detach from the pulp and need a period of stratification to prepare them for planting in the future. Tomato seeds are viable for four to five years if stored properly.
Tomatoes prefer warm temperatures. Seeds should be started indoors eight weeks before the final frost date for your region or planted directly outdoors once temperatures are in the 70s consistently. Seeds germinate in three to five days at this temperature. The seed leaves or cotyledons emerge first followed by the first true leaves. Indoor seedlings are treated to a hardening off process that prepares them to be moved outside when they are about 8 weeks old.
The next several weeks of the tomato plant's life is spent developing its framework. Stems, branches and foliage all develop for the sole purpose of producing the fruit. Determinate varieties grow until they reach a certain point and then stop and begin producing fruit, while indeterminate varieties continue to grow throughout fruit production until the first frost.
The first phase of fruit production is the blossoming of flowers. Flowers are pollinated followed by petal fall. At the terminal end of the flower stem, a small pea-like fruit begins to develop. This is the beginning of the tomato. Maturation of the fruit can take up to a couple of weeks depending on the tomato species and environmental conditions. Fruits can typically be considered ripe when they achieve their final color, most commonly a deep red.
Fruits are harvested over a period of a several weeks for determinate species or until the first frost for indeterminate species, which may be several months. In either case, the tomato plant simply stops growing and producing fruit. The leaves yellow, wilt and eventually fall. The plant withers and dries up. Fruits not harvested fall to the earth to decompose naturally and begin the cycle again. Other fruits may be harvested as food and some may provide the source of seeds for next year's garden.