Saving seeds from year to year will create plants that become acclimated to your area. Tomatoes are no exception to this rule. You should only choose the best and most ripe tomatoes in which to save seeds. The seeds, in most all cases, will produce plants and fruits that are as close as possible to the parent. Be sure that the flesh is completely intact with absolutely no bruising or insect damage. Breaks in the outer skin of the tomato, may allow bacteria or fungus to enter the flesh. This can create problems in the seeds.
Select the best tomato, that exhibits good characteristics. The fruit's characteristics will be of your own choosing. Preferences may include, numerous fruits on one branch of the plant, or tomatoes that have few seeds with large amounts of pulp for preparing sauces. Other favorable traits may be extremely large tomatoes for slicing and salads. One last consideration will be as to the prolific nature of the plant for your particular climate and length of growing season. Various climates will cause different tomatoes to grow with varying habits.
Cut the tomato in half with the knife. Squeeze the pulp and seeds from the tomato into the glass jar. Add approximately ½ inch of water into the jar with the seeds.
Cover the glass jar with the tight fitting lid. Set on a counter top. Allow the seeds, pulp and water to ferment for up to 3 days.
Pour off the fermented liquid and floating seeds, from the jar, into a sink. The viable good seeds will be sunk to the bottom of the jar. Add more clean water. Rinse the seeds.
Pour the good seeds through a small sieve. Collect the seeds on to a paper towel to dry.
Place the dried seeds inside an envelope. Use the pencil and mark the outside as to the date and variety of the tomato seed.
Store the envelope in a cool dry place, away from rodents and insects.