Several days ago, I decided to start another Black Prince tomato plant from seed and use it to replace my last and very poor looking Better Boy. I'm doing this because the Better Boy appears to be losing ground rapidly, while the Black Prince continues to thrive and put on fruit. Hopefully, the time it takes the Siberian heirloom's seeds to grow into transplantable seedlings will give the few (3) small tomatoes on the Better Boy a chance to ripen. That is, of course, assuming that the plant survives that long.
So, earlier this morning I planted several seeds that I harvested from a Black Prince tomato about a week ago. It is pretty simple to harvest seeds from tomatoes. Only try it with heirlooms, however, as any plant you get from a hybrid tomato may differ greatly from the plant that produced the seed. I used the following method:
Allow one a plant that you like to fully ripen, pick it, and cut it in half. Then scoop out the seeds with a spoon, knife, finger, or whatever you have. Now, dump this gooey mess into a cup, add a little water, and cover with the top with some wrap with a few holes punched in it. You'll want to remove the cover about once a day and stir the seeds. Soaking/fermenting in water helps remove the gelatinous coating from the seeds and some claim that it rids the seeds of any diseases that might be present. After the seeds soak for a few days, the top of the water will look pretty scummy. This is a good thing, as it lets you know the fermentation is taking place. Now remove the seeds, rinse them off, and spread them out one by one on a paper towel. Place the paper towel in an out of the way place and allow the seeds to dry for several more days (3 or 4 should do it). Once dry, they are ready to store or plant.
When the plants sprout, I'll thin them down over the course of several weeks to the strongest one and use it to replace the Better Boy.