Most seeds from vegetables can simply be harvested when mature, dried, stored, and used the following season.
Tomato seeds need to be fermented in their own juice to achieve a high germination rate. Tomato seeds are essentially encased in a gel sac the inhibits germination. This is to prevent mature seeds from germinating inside the tomato. The rotting and fermentation process takes place naturally when a tomato falls to the ground or rots on the vine. Nature naturally causes a fermentation process that removes the gel from around the tomato seeds. Once the gel is gone the seeds are more likely to germinate.
Fermentation not only removes the inhibiting gel, it also helps destroy many diseases that may be harboring around the seeds. The process of fermenting your tomato seeds also helps you identify the healthy seeds. The healthy mature seeds tend to sink to the bottom of the jar while the damaged or immature seeds remain caught in the floating gel mass of mold and goo.
Essentially you are creating an environment for the naturally fermentation process to occur. There are many variations on the way to start fermentation but they all describe the same process.
- Scrape the seeds and surrounding gel of 5 or more medium to large tomatoes into a jar
- Scrape the seeds and surrounding gel of 20 or more small or cherry tomatoes into a jar
- You want enough seeds and gel to ensure the fermentation process will start
- Do not include the meaty parts of the tomato
- Add 1 or 2 cups of water to the mix and make sure you have an ample amount of seeds and gel
- Seal the jar with a lid or a paper towel and rubber band
- Set the jar in an area with indirect light, like the top of your refrigerator
- Direct sun could cook the seeds by heating the jar through a green house effect
- Make sure the temperature of the jar stays above 70 degrees and below 90 degrees
- Watch for signs of fermentation which include mold build up and bubbling
- Shake the jar gently 1 time a day to mix the matter together
- The process should take 5-7 days, 5 days is typically all you need
- Don't forget to label the jar with the variety of tomato seeds you are fermenting
Typically the fermentation will be done in 5 days. You might need a few days longer depending on environmental factors. On the 5th day shake the jar in the morning and check it a few hours later. If the contents clearly separated then the seeds are ready to be collected and dried. Clear separation is when most of the tomato seeds are the bottom and the sour moldy gel is more so floating on top. Because you are mixing the jar gently each day you might not get distinct separation of colored liquid but the tomato seeds will have settled on the bottom in any case.
Collecting the seeds is fairly easy.
- Open the jar and scoop off the moldy gel (if needed) and gently pour out 2/3 of the liquid
- Pour the remaining liquid into a sieve and rinse the tomato seeds thoroughly with cold water
- Label a paper plate with the variety of tomato seed your are drying
- Place a coffee filter on the paper plate and spoon the seeds onto the filter
- Tomato seeds will stick to paper towels
- Let them dry, out of direct sunlight, for 5-7 days
- Rotate/swirl the seeds 1 or 2 times a day to help with uniform drying
Tomato seeds need to be totally dried before storing or they will mold. So take a few extra days to dry them when in doubt.
Tomato seeds can be stored in envelopes and placed in jar with a lid. Keep them as cool as possible and in the dark until they are needed next year. Don't forget to label the envelope with the name of the tomato seed variety.