How to save tomato seed
One can start collecting viable seeds for saving once the fruit reaches the "breaker" stage. This is when a small amount of color (usually red) shows up at the blossom end of the fruit. Still it is probably best to wait till one a fruit is fully colored. Selecting over-ripe fruit can result in reduced seed vigor and germination even though this is part of nature's method of removing the seed's gelatinous coat which contains germination inhibiting compounds. Over-ripe fruits can also result in precious seed germination in some cultivars (means the seed germinations in the fruit). Trying to speed up the ripening process up by utilizing ethylene (the gas which speeds ripening) can also result in reduced vigor and germination.
Fermenting the seeds will help to remove the gelatinous coat which contain gemrination inhibitors and helps reduce or destroy any pathogens present. Though messy/smelly, I recommend it.
Extract the seeds and put them in a marked container. Squeeze juice and seeds into 8oz-16oz plastic containers with lids (which will help too keep out insects, prevent spills and hold moisture) for about 2 days (it is also wise to label the container rather than the lid to prevent any mix ups). If one does use coverings, the container should not be set in direct sunlight. The warmer the temps, the quicker they ferment. 3 days or more may be needed in cool conditions. Rely on the fruit juices for moisture but add a small amount of water if needed to prevent drying. Too much water and the may start sprouting.
A mold should start forming on the surface but if it does not and its been 2 days that's ok. Just rinse the seeds well in a strainer and them tamp then out to dry. One can do so on paper towel, a plate, a screen or various other methods. It is important to dry seeds slowly, since rapid drying out shrinks the seed coat around the embryo and reduces seed quality (in terms of vigor). Good seed should be a light tan color. If you get dark brown seeds they may have set too long and germination will likely be reduced. If this happens do not worry too much, usually some will germinate the next year.
Store the seeds in the refrigerator and they should keep well for about 4 years. One can still get viable seeds 7-12 years later but usually the germination percentage is lower. If one plans to save seed this long be sure to save plently of seed. If one reduces the humidity this will increase seed life. This is done by adding a desiccant like silica to a container which will hold the packets of seeds. One can get desiccants from the packets of silica that come packed in electronics.
*If one suspects diseases treat seed in a 10% clorox solution for 10-20 minutes, then rinse, just PRIOR to sowing (NOT storage). This can reduce germination somewhat but can help to eliminate disease problems that may be associated with the seed. It cannot do anything for virus diseases however.
*If cleaning seed of different varieties do so one at a time so you don't mix up seed lots. A simple mistake like this can ruin a lot of hard work.
