Tomatoes are a relatively easy plant to care for, and can in fact be grown from the seeds of a store bought tomato. Ferment the seeds, plant them in the ground and place a cage or stake near the growing plant, and in only a few months you will have a wonderful, nutritious fruit.
The fermentation process
In order to eventually plant the seeds, you will first need to remove them and allow them to ferment. This is a lengthy and often times stinky process, but it is the best way to ensure success. Cut the tomato in half, and remove the seeds and some of the surrounding gelatin. Place the seeds and this material into a sterile, airtight container, and add a spoonful of water. Seal the top of the container with plastic seal and a rubber band, but poke a hole into the top of the seal for circulation. Ferment the seeds in a warm location, like a cabinet. Stir the mixture once a day. After two or three days, your tomato seeds should be ready to remove. Carefully remove the top part of the mixture, and add some water to what remains--seed and some additional materials. Run this through the sieve a few times with water, and you should be left with clean, fermented seeds. It is normal for them to emit a smell which some people consider offensive. Allow the seeds to dry for at least a week.
Planting the seeds
For best chances of success, you should start off growing your tomato seeds in seed starting soil-- available at gardening stores--which provides a much better nutrient content for seedlings than regular gardening soil. Sow the seeds about an 1/8 inch deep. According to HiIlary A. Rinaldi, certified organic farmer and editor of The Weekend Gardener, the best place for these seedlings during their first six to eight weeks is an appropriate container placed indoors.
Caring for the tomato plant
Seedlings should be transferred to an outdoor growing area once they have grown indoors for the appropriate time period. Planting the tomatoes on their sides gives the roots a better foundation for growth, according to Rinaldi. You should water the tomato plant regularly, but allow time for the soil to go dry between watering. Remove any diseased fruits or weeds from the tomato plant. Tomatoes which are given a stake or a cage will produce more fruit and will be cleaner because they do not spend any time on the ground. Depending on soil conditions and the weather, your plant will begin to produce fruit within a few weeks to a few months. Harvest the fruits when they are a solid color.
Many tomato experts agree that the taste of the tomato grown from a store bought tomato, unless it is a special variety, will usually be of a poor quality, regardless of what techniques are used to grow the plant. For this reason, if you want to grow the highest quality tomatoes, it is recommended to seek seeds from premium tomatoes or from seed distributors.