While it is a bit late in the season for some of this, I am including here for NEXT season.
You can start harvesting your seeds as soon as you have good healthy ripe tomatoes!
This is THE EASIEST way to save your heirloom tomato seeds! And it is a GREAT way to save money rather than buying them! You can do this with the organic ones you get from the farmer's market if you are not already growing your own!! :) But be sure to buy a GOOD one as you want to grow your plants next summer from good stock.
Pick a GOOD HEALTHY RIPE tomato to harvest your seeds from.. Cut off the bottom part and SQUEEZE the tomato to get the seeds out. You want some of the juice with it. A little bit of pulp is OK, but if you have a lot of pulp, you will want to remove it before continuing.
Put into a container (like a canning jar) and lightly cover. Put on the counter or out into the sun for a week to FERMENT. You want some mold (or what's called "the mother") to grow on it. Sounds gross, I know. But it really is a GOOD thing. It will kill off any seed borne diseases that might be in the seed.
Rinse off the seeds. Pour the seeds into a glass of water. The good seeds will sink to the bottom. Scrape off the bad seeds from the top, and drain the water and remaining good seeds. Dry the seeds well.
Store in freezer or a dry cool place until next spring. :D
A good video as well as a GREAT tip in here about planting seedlings:
Banana peels are GREAT for tomato plants! They contain phosphorus and potash which are valuable to the tomato plant. Especially before they are flowering. So chop a few up and bury in the soil when you transplant your seedlings! :) You can do it throughout the growing season as well.
Tomatoes that ripen in full sun have more vitamin C than those grown in the shade of their leaves. An easy way to remember that when pruning is to ask yourself "Are you growing leaves or are you growing tomatoes?" :D It might not look very pretty, but you will have some of the sweetest tasting tomatoes!